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Thermal modeling of greenhouse aquaculture raceway systems
Abstract
A mechanistic model was developed to describe the thermal behavior of an indoor raceway system with an inflated double polyethylene cover. The model describes the heat balances of the two covers, the inside air, the water in the raceway and the soil beneath the raceway. On-site measurements were made with an experimental system at the Waddell Mariculture Center in South Carolina. The collected data were used to calibrate the model. Comparison of the predictions with observations showed that the average absolute errors of air temperature and water temperature were 1.4 and 0.5°C, respectively and was 8% for the relative humidity. The accuracies are regarded as sufficient for the model to be useful for more general application. Model simulations were used to investigate the effects of the greenhouse on the air and water temperatures, to examine the heat fluxes and to calculate the heat consumption and costs at four different climatic locations. The results suggest that under the mild weather conditions in January near Charleston, SC where the daily mean temperature is 7.6°C and solar radiation is 121Wm−2, the inside air temperature increases by 5.6°C and water temperature increases by 9.7°C on average for the system with the 0.85m deep raceway covering 70% of the greenhouse floor. An examination of the heat fluxes suggests that thermal radiation is a major mechanism of heat loss for the greenhouse covers and the water surface. Convection from the water surface is also a significant mechanism for latent and sensible heat loss from the raceway. Reducing these heat flows will help conserve and utilize energy. The yearly heating requirements to keep the water temperature at 28°C for the experimental system were estimated to be 870, 520, 274 and 221 kWh per square meter of raceway for Syracuse, NY, Roanoke, VA, Charleston, SC and Baton Rouge, LA, respectively. The model was deemed to be a useful tool for exploring the performance of greenhouse raceway systems under different scenarios, such as different cover materials, sizes and climates.
... • Effects of water temperature: analyses the impact of water temperature on the optimal management of fish farms, the ration size, and fish weight. See papers (Khater 2015;Varga et al. 2020;Li et al. 2009;Besson et al. 2016;Hernández et al. 2007;León et al. 2006). • Dissolved oxygen prediction: special case of water quality problems with attention to the concentration of dissolved oxygen in the water. ...
... It also includes ecology-related problems of waste transportation in water objects. See papers (Kishi et al. 1994;Khater 2015;Li et al. 2009;Berstad et al. 2014;Liu et al. 2017). • Net-cage solidity: studies conduct numerical modeling and simulation of the mooring system tension of a fish farm. ...
... Usage of the mathematical modeling methods in aquaculture research: bio-economic models Spread of disease Green (2010) Engineering models Hydrodynamics Kishi et al. (1994) Kishi et al. (1994 Khater (2015); Li et al. (2009) ...
World aquaculture has demonstrated stable growth in production volumes for the last three decades. The competitiveness of the aquaculture market is growing steadily and the amount of data that fish-farmers have to manage is rapidly increasing. Mathematical modeling is the key factor in improving the fish farming industry and switching from experience-based to knowledge-based precision aquaculture. In this context, mathematical models are crucial tools for sustainable development. This paper presents a review of the literature on mathematical modeling in aquaculture. Using the scientific web search engine Google Scholar, we discovered 154 characteristic research papers considering mathematical models. We perform manual summarizing and classification of the papers by aquaculture problem, scale of the models, and methods used, and develop a classification. In total, we discovered mathematical models related to twenty different aquaculture problems and four scales, from cage/pool-wide to region-wide. We also describe the mathematical methods most commonly used and demonstrate examples of which specific mathematical methods are applied to solve aquaculture problems.
... Biological data -Other biological and physical chemical parameters [54,58] Thermal data -Greenhouse and thermal model parameters [28,59] Weather data -Hourly weather data press, while improving its optical properties to favour light penetration in the HRAPs. To this purpose, polyelectrolyte-assisted centrifugation with cationic polyacrylamide (CPAM) is used, which is common in sludge dewatering. ...
... Mechanical ventilation was the most cost-effective solution to avoid summer overheating, while more advanced thermal regulation strategies would only reveal cost-effective if cheap/waste energy vectors are available. Model simulations with the state-of-the-art ALBA (algae-bacteria) model coupled with a GH thermal model [59] and optimization studies performed on digestate in a similar climate [54] were used to define operational parameters and expected productivities (details on this model are reported later in Section 2.2.2). According to simulations, this section is expected to produce 76 t DW⋅y − 1 (9.8 g DW⋅m − 2 ⋅d − 1 ). ...
... The model includes CO 2 injection for pH control around optimal strain-specific values, as well as HRT/BRT decoupling. In this work, the ALBA model was coupled to mechanistic thermal models, allowing to simulate the effect of greenhouses or open-air configurations [28,59,69]. The combined thermal-biological model was used to simulate different scenarios of yearly temperature/irradiance profiles and operational conditions (HRT, BRT, liquid depth), in the presence/absence of the greenhouse. ...
The integration of microalgae cultivation in anaerobic digestion (AD) plants can take advantage of relevant nutrients (ammonium and ortho-phosphate) and CO2 loads. The proposed scheme of microalgae integration in existing biogas plants aims at producing approximately 250 t·y⁻¹ of microalgal biomass, targeting the biostimulants market that is currently under rapid expansion. A full-scale biorefinery was designed to treat 50 kt·y⁻¹ of raw liquid digestate from AD and 0.45 kt·y⁻¹ of CO2 from biogas upgrading, and 0.40 kt·y⁻¹ of sugar-rich solid by-products from a local confectionery industry. An innovative three-stage cultivation process was designed, modelled, and verified, including: i) microalgae inoculation in tubular PBRs to select the desired algal strains, ii) microalgae cultivation in raceway ponds under greenhouses, and iii) heterotrophic microalgae cultivation in fermenters. A detailed economic assessment of the proposed biorefinery allowed to compute a biomass production cost of 2.8 ± 0.3 €·kg DW⁻¹, that is compatible with current downstream process costs to produce biostimulants, suggesting that the proposed nutrient recovery route is feasible from the technical and economic perspective. Based on the case study analysis, a discussion of process, bioproducts and policy barriers that currently hinder the development of microalgae-based biorefineries is presented.
... Given the abundance of sunlight, solar thermal design solutions are potentially attractive. Past studies have shown a temperature gain of 5–9 • C when a greenhouse cover is used to cover tank and pond systems (Brooks and Kimball, 1983; Klemetson and Rogers, 1985; Zhu et al., 1998; Li et al., 2009). One method to potentially increase the effectiveness of a cover is to remove it during daylight hours and replace it at night. ...
... A model considers the various inputs and outputs of thermal energy for each part of a system (Singh and Marsh, 1996; Zhu et al., 1998). Significant work has been done to model greenhouse tank or pond systems (Zhu et al., 1998; Sarkar and Tiwari 2006; Jain, 2007; Li et al., 2009). When modeling a greenhouse covered aquaculture system, typical model inputs include weather data such as air temperature, solar radiation, humidity, and wind speed (Zhu et al., 1998; Sarkar and Tiwari 2006; Jain, 2007; Li et al., 2009). ...
... Significant work has been done to model greenhouse tank or pond systems (Zhu et al., 1998; Sarkar and Tiwari 2006; Jain, 2007; Li et al., 2009). When modeling a greenhouse covered aquaculture system, typical model inputs include weather data such as air temperature, solar radiation, humidity, and wind speed (Zhu et al., 1998; Sarkar and Tiwari 2006; Jain, 2007; Li et al., 2009). These data can either be measured by an onsite weather station or obtained from a variety of public databases depending on the location. ...
Temperature control is a major cost for numerous aquaculture systems. Solar thermal engineering techniques can be used to identify inexpensive methods for conserving and capturing heat. Gracilaria pacifica, also known as the culinary ingredient ogo, is currently grown in land-based tanks at a site in Goleta, CA where influent sea water temperatures infrequently reach the 21-28 °C range that provides for optimal growth. The major objective of this study was to explore various designs of a G. pacifica tank culture system that maintain optimal water temperature year round to maximize growth. A model was constructed and calibrated by comparing results to a one-third scale pilot system operated in Davis, CA. For model calibration the most sensitive parameter such as cover optical properties were adjusted first and less sensitive parameters were adjusted later. The pilot system consisted of six tanks, three insulated with foam and a clear polyethylene cover (experimental), and three uninsulated and uncovered (controls). The model had weather data inputs including air temperature, humidity, wind speed, and solar radiation. The model was then compared to a full-scale system operated in Santa Barbara during the winter. The experimental pilot system was 4.93 °C warmer than the control pilot system under optimal weather conditions. The full-scale experimental system was 2.80 °C warmer than the control system under non-ideal conditions. The model demonstrated predictive accuracy under most weather conditions. Furthermore the model is robust enough to accept estimated values for many inputs and still produce accurate results, this suggests a simpler model may be feasible. A polyethylene cover and insulation are not sufficient in general for raising the water temperature to the optimum range during the winter; they may be during other times of the year when more solar energy is available, thereby extending the growing season.
... Thermal modelling of the greenhousepond system: case study explanation As a practical application of the results provided in this study, a specific case study was considered, in which the energy consumption required to maintain an optimal growth temperature was calculated. In this case study, the CTMI model was coupled to a modified greenhousepond system (GPS) model that was originally developed by Li et al. (2009), allowing to assess yearly cumulated heating and cooling loads that are associated with temperature control in a microalgae cultivation system placed under a single-cover greenhouse. Within this framework, a temperature-controlled system was simulated using the software MATLAB R2021b (The Mathworks, Inc.). ...
... Nowadays, one of the most reliable methods to predict open pond cultivation temperatures is via mechanistic modelling of heat flux exchanges (radiation, sensible and latent convection, conduction) between the system and the surroundings (Casagli and Bernard, 2022a;Béchet et al., 2011;Casagli and Bernard, 2022b). When a greenhouse is adopted, mechanistic GPS models can be adapted to the specific case study, to assess the impact of, e.g., the covering system, both in terms of temperature and photosynthetically active radiation (PAR) availability, primarily depending on the greenhouse cladding material (Li et al., 2009;Casagli and Bernard, 2022b;Zhu et al., 1998;Sarkar and Tiwari, 2005). Similar physical models can be adopted to model the temperature and control systems in closed bioreactors (Mehlitz, 2009). ...
Microalgae and other phototrophic microorganisms can be cultivated to produce food and valuable bioproducts, also allowing to remove nutrients from wastewater and CO2 from biogas or polluted gas streams. Among other environmental and physico-chemical parameters, microalgal productivity is strongly influenced by the cultivation temperature. In this review, cardinal temperatures identifying the thermal response, i.e., the optimal growth condition (TOPT), and the lower and upper limits for microalgae cultivation (TMIN and TMAX), have been included in a structured and harmonized database. Literature data for 424 strains belonging to 148 genera of green algae, cyanobacteria, diatoms, and other phototrophs were tabulated and analysed, with a focus on the most relevant genera that are currently cultivated at the industrial scale in Europe. The dataset creation aimed at facilitating the comparison of different strain performances for different operational temperatures and assisting in the process of thermal and biological modelling, to reduce energy consumption and biomass production costs. A case study was presented, to illustrate the effect of temperature control on the energetic expenditure for cultivating different Chorella sp. strains under a greenhouse located in different European sites.
... The energy requirement for heating will depend strongly on the type of structure used, water components, and local climatic conditions. Under mild winter conditions in Charleston, SC, Li et al. (2009) found that a greenhouse with a double plastic cover could increase the water temperature by 5.6 C and the air temperature by 9.7 C. ...
... Commercial heating units using natural gas, propane, or diesel have been used in hydroponic and aquaponic systems. To maintain a water temperature of 28 C at Charleston, 221 kWh/(m 2 y) was needed with an annual energy cost of $10.36/m 2 (Li et al. 2009). The annual energy costs at Syracuse, NY, a much colder site, was $40.89/m 2 . ...
Aquaponics is the integration of aquaculture and hydroponics where nutrients released by growing fish are utilized by plants grown in a soilless culture, often in a controlled environment. Potential advantages of aquaponics include improved sustainability, reduced resource consumption, and fewer environmental impacts compared to conventional aquaculture. Based on a 2014 survey, it was found that most respondents were practicing aquaponics as a hobby. Other groups of respondents were educators, non-profit organizations that operate aquaponic systems, commercial operators, and consultants that sell goods, material, and services. Although many proponents cite the opportunity to create a commercially viable food production system few (if any) ventures have demonstrated sustainable financial outcomes. In general, much of the peer-reviewed aquaponic publications and popular literature, and despite the efforts of some investigators, lacks a methodical scientific basis for describing the essential mechanics, relationships, and culture methods within aquaponic systems. Many systems evolved from small-scale experimental facilities devised by trial and error methods and were implemented with locally limited appropriate species, limited finances, and distorted market situations. Many of the published aquaponic experiments are based on small systems, short growth trials, and weak experimental design. The predominant system design approach is based on a relatively small number of experiments. This review introduces notation and algorithms that are intended to standardize the numerous critical values essential in aquaponics for purposes of determining design criteria and operational parameters including flows, the concentration of water quality constituents, metabolite production, and productivity of plant and animal segments in an aquaponic systems. The objective of this systematic approach is to employ scientific methods that provide research results that can be replicated, challenged, and improved. This methodology is expected to facilitate more rapid development of scientific information, productive systems, and rational economic applications. This approach is crucial for commercial applications where production cost, product value, and investment returns are of critical importance for practitioners that envision investment in new ventures. For hobbyists and educators, economic issues may not be as important as the self-sufficiency and natural synergism aspects, personal satisfaction, and the learning experience that result from existing state-of-the-art of aquaponic practices. These outcomes remain for all and a clearer understanding of smaller personal systems is likely to be enhanced.
... To the best of our knowledge no study reports the thermal modeling of biofilm photobioreactors. Previous thermal modeling efforts concentrated on other PBR designs such as greenhouse raceway ponds, vertical flat plate PBRs, cylindrical tanks, and tubular PBRs [7,91011. In a study performed by Gutiérrez et al. [7] , a computational heat transfer model was validated against experimental temperature data for a cylindrical tank outdoor open PBR. ...
... They indicated that the characteristic evaporative mass loss rate for this PBR was approximately 4 L/m 2 day. Moreover, Li et al. [11] constructed and validated a thermal model of a raceway system within a greenhouse. The raceway had a depth and footprint area of 0.85 m and 280 m 2 , respectively, and it was enclosed in a greenhouse with a height and footprint area of 3.5 m and 400 m 2 , respectively. ...
This study describes the thermal modeling of a novel algal biofilm photobioreactor aimed at cultivating algae for biofuel production. The thermal model is developed to assess the photobioreactor's thermal profile and evaporative water loss rate for a range of environ-mental parameters, including ambient air temperature, solar irradiation, relative humid-ity, and wind speed. First, a week-long simulation of the system has been performed using environmental data for Memphis, TN, on a typical week during the spring, summer, fall, and winter. Then, a sensitivity analysis was performed to assess the effect of each weather parameter on the temperature and evaporative loss rate of the photobioreactor. The range of the daily algae temperature variation was observed to be 12.2 C, 13.2 C, 11.7 C, and 8.2 C in the spring, summer, fall, and winter, respectively. Furthermore, without active cooling, the characteristic evaporative water loss from the system is approximately 6.0 L/m 2 day, 7.3 L/m 2 day, 3.4 L/m 2 day, and 1.0 L/m 2 day in the spring, summer, fall, and winter, respectively. [
... The dynamic greenhouse thermal model taken as reference was developed by Li et al. and describes shallow ponds for aquaculture purposes covered by a GH equipped with two cover layers [34]. It is a mechanistic conceptual/gray-box model, based on the modeling of the major heat exchange mechanisms and heat/mass balances across each component of the system. ...
Spirulina is a microalga recognized for its nutritional benefits and its potential in sustainable food production. Existing large-scale cultivation produces spirulina of very different quality, taste, and odor. The reason lies in various approaches to the production, which range from the low-technology simple systems to high-end high-quality production for more demanding consumer market. In this chapter, we present challenges and possible solutions to ensure production of high-grade spirulina. We describe the design and crucial demands that have to be assured in the production system. The quality and productivity can be further increased by applying a bioprocess engineering approach based on modeling of the cultivation. Thermal modeling is also presented as an approach to optimize cultivation in the greenhouse systems. A spirulina production in Italy is showcased to pinpoint challenges of spirulina production in Europe. We conclude with an extensive study of regulatory framework for the spirulina production that must be taken into account for the successful algae production.
... The thermal model for the open-air configuration was implemented as done by Casagli and Bernard [46,47]. Thermal models for the cultivation under greenhouses (either one or two covers) were implemented according to Rossi et al. [48], based on the greenhouse-pond model derived by Li et al. [49]. All the described thermal sub-models have been previously calibrated and validated in similar climatic conditions and treating similar wastewaters. ...
Microalgae cultivation on liquid digestate from the anaerobic co-digestion of agricultural feedstocks is an interesting option for digestate nutrient removal and resource recovery coupled to biomass generation. Both the reactors considered in such a biorefinery system involve complex bioprocesses. Although different pilot-scale systems coupling anaerobic digestion and algae-based bioremediation processes have been described, no previous attempts to model the entire system are available to date. In this work, a plant-wide model, named ADAB (anaerobic digestion algae-bacteria), is presented, coupling two well-established models for anaerobic digestion (IWA – ADM1) and algae-based bioremediation processes (ALBA). The models were modified with necessary equations and extensions to develop a dedicated model interface. Phosphorous dynamics were integrated, including activity corrections and precipitation processes. The ALBA model was also integrated with thermal modelling to simulate outdoor raceway ponds and greenhouse-covered systems. Solid/liquid separation units for digestate pre-treatment were also included. The prediction consistency of the adopted physicochemical sub-model (PCM) was verified with results from both reference literature and Visual MINTEQ. The reduced complexity of the PCM limits the model field of application, but it results in better computational performance and seems to be particularly suitable to simulate agro-zootechnical digesters. A scenario analysis including different co-digester design and operating conditions was carried out to assess the impacts on microalgae cultivation. It highlighted the importance of a proper biorefinery design and yet a noteworthy robustness of the system performance. The use of the ADAB model can facilitate a more realistic assessment of the technical, environmental, and economic feasibility of full-scale microalgal biorefineries based on digestate.
... In northern China, the greenhouse flow-through aquaculture system has been widely used during the overwintering period. Greenhouse structures, commonly used in agricultural production, are being recognized as economical options for indoor aquaculture because greenhouses are generally inexpensive structures to erect (Li et al. 2009). Greenhouses can be used to maintain a constant water temperature. ...
Tiger puffer (Takifugu rubripes) is one of the most expensive farmed marine fish species in China. The high profitability of farmed tiger puffer is used to attract many new investors. However, some investments failed due to a lack of information about the tiger puffer fish farm business, poor farm and facility design, and flawed investment plans. To improve the investment efficiency and profitability of this industry, this analysis evaluated the economic performance of tiger puffer from eggs to harvest size using two different open-indoor combination aquaculture systems: a combination of recirculating aquaculture system and open net pen (RAS+ONP) and a combination of flow-through system and earth pond (FTS + EP). This analysis evaluated the financial performance of both systems using profit margin, net present value (NPV), internal rate of return (IRR), and payback period. At the same time, a sensitivity analysis was employed to measure economic risk. The results revealed that despite the RAS+ONP system being more economically profitable than the FTS + EP system, the financial indicators of the FTS + EP system granted a better economic performance in terms of NPV and IRR due to lower initial investment and operating costs. Meanwhile, the sensitivity analysis revealed that the economic performance of both systems was vulnerable to the fluctuations in fish prices and feed prices. The potential risk of earning profit was higher for the RAS+ONP if the feed price fluctuated compared to the FTS + EP system, while the risk was higher for the FTS + EP if the fish price fluctuated. Hence, the FTS + EP system could represent an opportunity for new entrants to obtain a more profitable production.
... Keeping the night temperature high in the outdoor environment is low-cost when using a greenhouse. Other research groups have also reported that the use of greenhouses can raise the temperature of raceway ponds by as much as 10 • C [35]. Assuming that the price of Arthrospira is 15 USD kg − 1 as a commercial-based average from several websites and that the areal productivity at 15 • C during dark period is 12 g m − 2 d − 1 obtained in this study, the profit would be 0.17 USD m − 2 d − 1 . ...
Heating cost during the night is a problem in outdoor cultivation of a cyanobacterium Arthrospira platensis. Low night temperature causes decreased biomass productivity during daytime and biomass loss during night, but there are few studies to fully investigate these impacts at the same time. To evaluate the effect of dark-period temperature (10–35 °C) on the net productivity (g-DW L⁻¹ d⁻¹) of Arthrospira platensis, semi-continuous cultivations were conducted in 1-L cylindrical glass photobioreactors with an LD cycle of 12-hour light and 12-hour dark under a light-period temperature of 35 °C and dark-period temperatures between 10 and 35 °C. By monitoring at 12-hour intervals, daytime productivity (g-DW L⁻¹ d⁻¹) and night biomass loss (%biomass) were investigated to understand net productivity. There was no significant difference in the net productivity and daytime productivity at high dark-period temperatures (25, 30 and 35 °C). On the other hand, at lower dark-period temperatures (10 and 15 °C), the net productivity and daytime productivity were at most 30% lower than that recorded at higher temperatures (25 and 30 °C). The dark-period temperatures were negatively correlated with carbon to nitrogen (C:N) ratio and positively correlated with dark-respiration rates, which suggested low protein synthesis at low dark-period temperature leading to the low net productivity at 10 and 15 °C. The tolerance of Arthrospira platensis to low dark-period temperature (25 °C) indicates possible cost reduction to control temperature during dark period. This study clarified that the low night temperature reduced net productivity of microalgae and cyanobacteria, and night temperature should be managed in outdoor cultivation based on the permissible dark-period temperature range.
... The state-space coefficient matrix can also be derived in terms of resistors and capacitors based on the thermal properties of the greenhouse cover. Li et al. [201] investigated the thermal modeling of a greenhouse-aquaculture raceway system, analyzing the thermal dynamics of components of the greenhouse-aquaculture system. The heat balance equation for the model was solved numerically, with simulation results in close agreement with measured data. ...
With growing food demand worldwide, controlled environment agriculture is an important strategy for crop production year-round. One of the important types of controlled environment agriculture is greenhouses. Key indoor environmental parameters such as carbon dioxide, moisture, lighting, and temperature are required to be maintained for favorable crop growth in greenhouses. Due to lightweight construction and inefficient operation, greenhouses consume more fossil fuel energy in the operation of mechanical systems than other similar sized buildings and have larger carbon footprints. In fact, greenhouses are one of the most energy-intensive sectors of the agricultural industry. Energy consumption in greenhouses is influenced by mechanical systems, indoor environment, crop growth, and evapotranspiration. Therefore, energy simulations help analyze the complex thermal processes in greenhouse operation, and contribute to energy efficient greenhouse operation. This paper reviews existing strategies on energy efficient control operation and state-of-the-art energy simulation for greenhouses. It first discusses strategies for improving energy efficiency in greenhouse control operation by summarizing the studies on energy efficient operation strategies, the control of key greenhouse parameters, sensing network and monitoring systems, along with various control algorithms. Second, the review covers energy modeling of greenhouses by summarizing existing and developed approaches. Finally, this review identifies areas in which future research has the potential to reduce greenhouse energy consumption and carbon footprint.
... The model presented by Kumar and Tiwari can also is used for indoor as well as an outdoor simulation for any shape of condensing cover and operating temperature mode. The proposed model can be also used for other applications namely solar crop drying (Forson et al., 2007;Ratti and Mujumdar, 1997;Tiwari et al., 2004;Kumar and Tiwari, 2006); open swimming pool (Dongellini et al., 2015;Zhao et al., 2018), greenhouse aquaculture (Jain, 2007;Li et al., 2009) and solar pond (Valderrama et al., 2016;Kurt et al., 2000;Weinberg, 1979) etc. ...
In the present paper, an attempt has been made to simulate the performance of solar still by using iteration method for an internal convective heat and evaporative (mass) transfer coefficient which are used in basic energy balance equations. The energy balance is based on the first law of thermodynamics as a function of design and climatic parameters respectively. The internal convective heat transfer coefficient plays a significant role in the performance of solar still. The iteration method based on Kumar and Tiwari model (KTM), which has not been considered earlier by any authors, has been adopted for numerical computation for the convective heat transfer coefficient (hcw). Based on numerical computation for New Delhi climatic condition, it has been observed that the numerical values of hourly change of an internal convective heat transfer coefficient (hcw) vary between 1.3 to 1.5 W/m2 0C, after fourth iteration process which is reduced by 11.7% in comparison with the first iteration.
... The use of limited water-exchange production systems in greenhouses, such as that employed in biofloc technology (BFT), is an alternative to increase the period of farming in subtropical regions, reducing water exchange and minimizing heat loss (McAbee et al., 2003;Arnold et al., 2009;Crab et al., 2009;Li et al., 2009). The intensive production of shrimp post-larvae has been gaining more attention worldwide, with the potential to improve production in aquaculture through the application of a transitional nursery system. ...
This study evaluated different stocking densities during pre-nursery of Pacific white shrimp post‑larvae (PL) reared in a biofloc system. The tanks (60 L) were stocked with PL stage 5 (PL 5) under five densities (80, 100, 120, 140 and 160 PLs L-1), in triplicate, resulting in 15 experimental units. PLs were fed nine times a day using commercial feed. Molasses was added in all treatments four times a day at an average carbon: nitrogen ratio of 14.7: 1. The experiment was carried out until the PLs reached PL 20 stage, and during this time, water quality variables, survival, weight gain and survival to salinity stress were all evaluated. For treatments above 100 PLs L-1, total suspended solids were higher than recommended (700 mg L-1). Also, the treatment with 160 PL L-1 had higher total ammonia nitrogen peaks (>10 mg L-1), resulting in lower survival in this treatment. No differences were observed between treatments in the other performance parameters evaluated (final weight and survival to salinity stress). It was concluded that pre-nursery of Pacific white shrimp can be performed using densities up to 140 post-larvae L-1 in a biofloc system without compromising shrimp growth performance.
... Consequently, most soft-shelled turtle farmers employ closed greenhouse system for overwintering and for an early start-up. In the greenhouse, air and water temperature are controlled constant around 32 and 30°C, respectively, which are optimal for the turtle's growth (Li et al. 2009). ...
Chinese soft-shelled turtle (Pelodiscus sinensis) is a favorite food for the Asian because of its high nutritional and medicinal value. Based on an estimate production of 350,000 MT in 2015, soft-shelled turtle culture industry in China values US$5.22 billion. In central China, overwinter in greenhouse is necessary for the juvenile turtle. The use of coal boiler to heat up the water to 30 °C is a common practice, however, brings in air pollution and CO2 emission too. A modern greenhouse equipped with ground source heat pump was built in 2010 and operated during 2014–2015 for 10 months to culture juvenile turtle. Besides heating system, the other innovative features such as skirt-shaped 3-D shelter, underwater feeding platform wok-shaped tank bottom with central drainage, and semi-homemade soft shell-shaped pellet together achieved excellent rearing performance, such as high turtle productivity of 23.7 kg m⁻², high survival 86%, low feed efficiency-feed conversion rate 1.26 and good water quality-dissolved oxygen >5 mg L⁻¹, and nitrite and ammonia concentration all time within safe range. Moreover, it is a lucrative business which brought in an estimated net profit of 76%.
... However, for outdoor systems it is more complex or even impossible, as in net cages, to control the water temperature because of heat losses to the environment [44]. In order to contradict those difficulties, steps have been taken to simulate and predict temperature changes for different systems exposed to heat losses [44,45] and to identify thermal characteristics of systems [46]. Water temperature can also be controlled in a more indirect way, such as with water exchange, where the temperature of the water entering the system can be manipulated [22]. ...
The aquaculture sector has been increasing its share in the total fish production in the world. Numerous studies have been published about aquaculture, introducing a variety of techniques and methods that have been applied or could be applied in aquaculture production systems. The purpose of this study is to present a systemic overview of the functions of aquaculture production systems. Each function of an aquaculture system is applied to carry out a certain purpose. The results are divided into three sets of functions: input, treatment, and output. Input functions deal with what happens before the rearing area, treatment functions are about what happens inside the rearing area, and output functions is what comes out of the system. In this study, five input functions, ten treatment functions, and five output functions are indentified. For each function the controlling parameters or indicators were identified and then a list of possible methods or technological solutions in order to carry out the function was compiled. The results are presented in a system map that aggregates all functions used in different types of aquaculture systems along with their methods of solution. This is the first of four articles that together generate taxonomy of both means and ends in aquaculture. The aim is to identify both the technical solutions (means) that solve different functions (ends) and the corresponding functions. This article is about the functions.
... Water temperature attains maximum at 16:00 and minimum in the early morning 4:00 to 5:00 for greenhouse [30]. Water temperature can be maintained higher in greenhouse system [9], [10], [31]. In greenhouse systems, water is an excellent medium for the collection and storage of solar energy, thus an aquaculture system can function as a passive solar collector and heat stored in solar architecture [32]. ...
Currently, aquaculture based employment has been impact on fishery industry and gained awareness in worldwide. Northern parts of Thailand, Cage fish farming are very important cultivation. It has contributed substantially to livelihoods, food demand, employment and income. Environmental factors are significant role in the fishculture especially, the temperature. It is fairly low in the Northern part of Thailand during in the winter, air temperature drops below 15 °C and difference between day and night about 15-20 °C. Generally, the appropriate and optimum temperature of fish culture was 28-32 °C. The average initial weight of fishes were 2.54±0.11g at cultured for 120 days in 3 treatments, normal fish cage (T-A), greenhouse fish cage (T-B) and greenhouse fish cage was integrated with reduce heat loss system (T-C). The study investigation revealed that average water temperature and highest value were observed in treatments (T-C) (27.6 °C), followed by treatments (T-B) (26.7 °C), and treatments (T-A) (26.4 °C), respectively. After 120 days of culture, fishes in treatments (T-A) had significantly higher weight (121.35±5.33 g/fish) then treatments (T-B) (135.05±5.66 g/fish) and treatments (T-C) (143.87±5.07g/fish). Compared treatments (T-C) with treatments (T-A) and (T-B) achieved more than daily weight gain equal to 16.1% and 6.8%, respectively. Also the specific growth rate was equal to 4.17% and 1.49%, respectively. Furthermore, the study focused on increasing and provides the optimum temperature using thermal performance of greenhouse fish cages integrated with hot air aerator through solar energy. In this study, Climbing perch (Anabas testudineus) fish was used. The system was developed for heating the fish cages with solar energy by greenhouse cage design equipped with insulation to reduce heat loss by used foam and covered with bamboo which is economically helpful for fish farmer. Consequently, the results confirmed that possible to apply and increase water temperature through greenhouse fish cage integrated with reduce heat loss system.
... The use of greenhouse-enclosed shrimp biofloc culture rearing system (BFT systems) is a technology that makes it possible to increase the culture period in higher latitudes by reducing water exchange and minimizing heat loss (McAbee et al. 2003;Arnold et al. 2009;Crab et al. 2009;Li et al. 2009). However, culture intensification is necessary in order for this 1 Corresponding author. ...
... The model simulated energy balances and the equations were solved with an hourly time step. Li et al. [25] used a mechanistic model to study the thermal behaviour of a system including inner heat storage (internal channel with water) in a greenhouse with double polyethylene cover. The model consisted of higher-order algebraic equations, which were solved by the process of repetition, with successive time steps. ...
The intensive greenhouse energy requirements are a major operational and economical problem for producers around the world. Energy conservation techniques and innovative applications of solar energy for heating are being employed in greenhouse operation to reduce heating costs during cold periods. The present study investigated the development of a mathematical model to predict the thermal efficiency of a novel hybrid solar energy saving system inside a heated greenhouse. The solar system consisted of
a transparent water-filled polyethylene sleeve and two perforated air-filled polyethylene tubes on the top peripheral sides of it. Above the sleeve and between the two tubes, rockwool substrates were placed for hydroponic cultivation of tomato crop. In order to validate this model, experiments were carried out in two identical parts of a polyethylene arched-type greenhouse to obtain data during winter. By comparing the measured and the predicted values, a correlation of 95% was found, indicating that the model can simulate the water temperature inside the hybrid solar sleeves. Moreover, the additional energy provided by the hybrid solar system reached approximately 23% during the examined period, depending on solar radiation levels.
... Cage culture Kim et al., 2011DeCew et al., 2010Zhao et al., 2010Lee et al., 2008Huang et al., 2006Fredriksson et al., 2003 Pond culture Gutiérrez-Estrada et al., 2012Bolte et al., 2000Jamu & Piedrahita, 1998Hargreaves, 1997Gao & Merrick, 1996Leung & Shang, 1989Brooks Jr & Kimball, 1981 Raceway systems Li et al., 2009 Recirculating systems Halachmi, 2006Halachmi et al., 2005Weatherley et al., 1993 Process time and output for different inputs of incoming materials (total entities) for high-throughput cryopreservation of blue catfish sperm. The ARENA model simulated each scenario 50 times and presented the mean ± SD for the process time and number of daisy goblets produced. ...
Emerging commercial-level technology for aquatic sperm cryopreservation has not been modelled by computer simulation. Commercially available software (ARENA, Rockwell Automation, Inc. Milwaukee, WI) was applied to simulate high-throughput sperm cryopreservation of blue catfish (Ictalurus furcatus) based on existing processing capabilities. The goal was to develop a simulation model suitable for production planning and decision making. The objectives were to: (1) predict the maximum output for 8-h workday; (2) analyse the bottlenecks within the process, and (3) estimate operational costs when run for daily maximum output. High-throughput cryopreservation was divided into six major steps modelled with time, resources, and logic structures. The modelled production line processed 18 fish and produced 1164 ± 33 (mean ± SD) 0.5-mL straws containing one billion cryopreserved sperm. Two such production lines could support all hybrid catfish production in the United States and 15 such lines could support the entire channel catfish industry if it were to adopt artificial spawning techniques. Evaluations were made to improve efficiency, such as increasing scale, optimizing resources, and eliminating underutilized equipment. This model can serve as a template for other aquatic species and assist decision making in industrial application of aquatic germplasm in aquaculture, stock enhancement, conservation and biomedical model fish.
... The DWG and survival in mode-G were significantly higher than those in mode-C, possibly due to the relatively high water temperature in the early culture period. It has been reported that the greenhouse-enclosed system enhanced shrimp growth by increasing the water temperature (Li et al., 2009;Huang et al., 2010). ...
Different culture methods may affect the intensive culture system of Pacific white shrimp (Litopenaeus vannamei) regarding water quality and growth and economic performance. This study evaluated the potential effects of three culture methods through cultivation of juvenile shrimps under consistent tank management conditions for 84 d. The three methods involved shrimp cultivation in different tanks, i.e., outdoor tanks with cement bottom (mode-C), greenhouse tanks with cement bottom (mode-G) and outdoor tanks with mud-substrate (mode-M). Results showed that water temperature was significantly higher in mode-G than that in mode-C (P < 0.05). In contrast to the other two treatments, mode-M had stable pH after 50 d cultivation of shrimps. In the mid-late period, the average concentrations of TAN, NO2-N, DIP and COD were significantly lower in mode-M and mode-G compared with those in mode-C (P < 0.05). Despite lack of differences in the final shrimp weight among different treatments (P > 0.05), mode-M had significantly higher shrimp yield, survival rate and feed conversion rate (P < 0.05) than other modes. There were significant differences in revenue and net return among different treatments (P < 0.05). These demonstrated that the treatments of mode-G and mode-M were conductive to the intensive culture system of L. vannamei.
Large seasonal temperature variations in aquaculture source water leaves aquaculture ponds and raceways susceptible to temperature variations leading to non-optimal growing conditions. Such conditions may slow down the growth rate and make aquatic species vulnerable to disease and potential death, leading to economic setback for aquaculture farmers. Therefore, it is advantageous to predict the temperature of aquaculture raceways under the influence of seasonal variations and study the parameters that contribute to these variations. This allows one to develop strategies and processes to better regulate the raceway temperature to maximize its productivity. A numerical energy model was developed to simulate the temperature of water inside an aquaculture raceway, and a parametric study was conducted to investigate the influence of various key parameters on the raceway temperature. It was found that surface area and flow rate have a large effect on the raceway temperature, while depth of raceway had little effect. The largest surface area tested produced outlet temperatures and heat transfer values that were 6.2% and 76% higher, respectively, than the smallest surface area tested. Decreasing flow rate from the reference value of 43 L/s to 1 L/s resulted in an 83% increase in average outlet temperature. It was also observed that the variations in the ambient air temperature alone has negligible effect on the raceway temperature. The model was further implemented to simulate the temperature of raceways located at different geographical locations.
The heating system for the aquaponics greenhouse is crucial to realize economical and efficient hydroponics and aquaculture in cold climate zone. This paper investigated the technical feasibility and economics of a heat pump heating system in the aquaponics greenhouse and compared it with the original heating system. A mathematical model of technical and economic analysis under different heating modes was established. Using the mathematical model, different heating systems were contrasted with their primary energy consumption, pollution emissions, and winter operating cost. The results show that in a heating cycle in winter, the experimental air source heat pump (ASHP) and ground source heat pump (GSHP) save 8,959 CNY and 13,881 CNY, respectively, compared with coal-fired boilers, and reduce CO2 emissions by 53.0% and 62.2%. Heat pump heating systems have relatively high energy efficiency, relatively low dioxide pollution emissions, and economical way.KeywordsAquaponics greenhouseHeating systemHeat pumpOperation costCarbon emissions
Probiotics are increasingly used in aquaculture to protect cultivated organisms from pathogens and improve water quality and feed efficiency. Shrimp are the most commonly cultivated aquaculture species worldwide. In this current review, we will explore the current challenges that impact shrimp aquaculture and summarize how probiotics are utilized to improve production. Probiotics are live microorganisms that are described as friendly bacteria or healthy bacteria supplemented to the shrimp gut through feeds. Probiotics have been demonstrated to increase gastrointestinal stability, secrete antibacterial compounds, compete with pathogens to prevent intestinal adhesion, compete for the nutrients required for pathogen survival and produce antitoxin effects. Probiotics can also modulate the immune system and control the allergic response of the body. Therefore, this review sheds light on the challenges faced in shrimp production as well as the different types of probiotics, their methods of application, their modes of action, their role in improving shrimp production, and their influence on water quality.
Controlled Environment Agriculture (CEA) applications, such as vertical farms and plant factories, have the potential to shift food production to be close to urban centers helping meet demands of large populations as well as achieving global climate goals. Growing crops in controlled environments has proven to be feasible for several applications, however, most involve energy intensive processes. The review analysis presented in this paper seeks to overview current CEA practices as well as potential energy efficiency technologies that can enhance the sustainability and the profitability of the indoor farming industry. Specifically, the paper reviews various CEA techniques, optimal indoor growing environments, successful case studies, and recommended energy systems research. The review analysis indicates that changes to a facility's envelope, HVAC, lighting, and incorporation of distributed generation technology can reduce consumption of electricity up to 75% in several CEA case studies. Future research into controls, dehumidification, lighting, and crop variety are vital for a wider adoption of CEA applications.
This study describes the makeup of and results from a simulation consisting of a lumped thermal model integrated with a dynamic algae growth model to simulate the microalgae productivity of an open-channel raceway cultivation system. The thermal model considers the dynamic effects of weather, light absorption, convective heat transfer, radiation heat transfer, conductive heat transfer, thermal capacitance, and water control strategies. The dynamic algae growth model solves a set of ordinary differential equations consisting of growth functions dependent on incident radiation, temperature, nutrient availability, basal metabolism, and losses due to dark- and photo-respiration. Relative errors in the predicted ash-free dry weight of Nannochloropsis oceanica are 12.5%, −6.1%, and 4.4% for three separate replicates of cultivation cycles (~4.2 m²) performed at AzCATI during the ATP³ Unified Field Studies in Fall, Spring, and Summer. This research demonstrates that thermal modeling is an essential contributor to the validation of microalgae growth models.
The paper presents results of the analysis related to determination of the value of the coefficient of heat permission through the cover of a facility and thermal issues (temperature, heat amount) at discharging a stone accumulator. For calculation of this coefficient, relation including inside temperature change as a function of variable amount of heat transferred to the cover by radiation and heat transferred outside the facility by permission was used. Basing on the value of the calculated coefficient of heat permission the value of temperature inside the plastic tunnel in the process of supplying heat from a stone accumulator was determined. At the accepted decision values (temperature of surrounding is 8ºC, initial temperature in the tunnel at the level of 15ºC and the stream of pumped air amounting to 500 m3·h-1) and at the accepted cycle of discharge (9 hours), the scope of temperature changes inside (in comparison to the initial value) was within -0.2 to 2.4 K. Moreover, simulation calculations of the impact of the heat supplied from the accumulator, where initial temperature of the accumulator and stream of pumped air were included as variables, on the final values of the soil accumulator temperature, were carried out. Furthermore, quantity relations between final temperature of the accumulator and its room temperature and the stream of pumped air were determined. Non-linear estimation with the use of quasi-Newton method was applied for determination of this relation.
It is very important to maintain an optimum inside environment during the different stages of aquatic animals growth for modeling thermal behavior of aquaculture greenhouse. A mechanistic model was developed to describe the thermal behavior of a shading turtle greenhouse system with polystyrene foamed plastic envelope. Energy balance equations have been written considering the effects of conduction, convection, radiation, evaporation and ventilation. Numerical computations have been performed for special days in the month of January 2012, under the climatic conditions of Hangzhou in Eastern China. The governing equations are numerically solved using Matlab 7.0 software to predict the inside and outside surface temperature of the envelope, room temperature, relative humidity, and water temperature. At the same time, on-site measurements were taken at a turtle-breeding facility in Hangzhou for comparisons with predictions. Results showed that the average absolute errors of air temperature, water temperature, and relative humidity were 1.3, 0.32°C and 3%, respectively. The results also showed that the internal air temperature and water temperature could maintain a relatively stable state by using two sets of 2.7 kW ground-source heat pumps for the turtle greenhouse heating (about 540 m2), a suitable thermal environment for the turtles growth. Model simulations were used to investigate the effects of the greenhouse on the air and water temperature and to examine the heat fluxes. The results suggest that the daily mean temperature is 5.8°C, the solar radiation is 132 W/m2, the room temperature maintains 35°C, and the water temperature maintains 30°C when the heat pump provides 40 W/m2 in January near Eastern China-Hangzhou. An examination of the heat fluxes suggests that thermal radiation and underground heat conduction are major mechanisms of heat loss for the greenhouse covers and water. About 44.5% of heat loss was caused by underground heat exchange, about 43% by built envelopment heat exchange, and about 12.5% was by air leakage. Reducing these heat fluxes will help conserve and utilize energy. Moreover, the model was deemed to be a useful tool for exploring the performance of heating greenhouse systems under different scenarios, such as different cover materials, sizes and climates.
Bioflocs Oxygen dynamics Resuspension, mixing, and sludge management Nitrogenous waste products Temperature Feeds and feeding Economics Sustainability Outlook and research needs Acknowledgment References
This study describes the thermal modeling of a novel algal biofilm photobioreactor aimed at cultivating algae for biofuel production. The thermal model is developed to assess the photobioreactor's thermal profile and evaporative water loss rate for a range of environmental parameters, including ambient air temperature, solar irradiation, relative humidity, and wind speed. First, a week-long simulation of the system has been performed using environmental data for Memphis, TN, on a typical week during the spring, summer, fall, and winter. Then, a sensitivity analysis was performed to assess the effect of each weather parameter on the temperature and evaporative loss rate of the photobioreactor. The range of the daily algae temperature variation was observed to be 12.2°C, 13.2°C, 11.7°C, and 8.2°C in the spring, summer, fall, and winter, respectively. Furthermore, without active cooling, the characteristic evaporative water loss from the system is approximately 6.0 L/m 2 day, 7.3 L/m 2 day, 3.4 L/m 2 day, and 1.0 L/m 2 day in the spring, summer, fall, and winter, respectively.
Water temperature plays a relevant role in the growth and development of plants in floating system
cultivation, thus affecting both productivity and quality. A model of a greenhouse which hosts ponds is
described, in order to highlight the components of the energy balance and estimate the refrigerating
power required to maintain the nutrient solution within acceptable limits. A water cooling plant powered by an electrical water chiller is considered. Results from this model include the prediction of the air
temperature and nutrient solution temperature in transient conditions during the growth periods,
together with the electrical energy absorption and related operating costs. After a validation by comparison with measured data, simulations are performed at six climate conditions, from typical warm
Mediterranean to cold continental conditions.
Important energy savings can be achieved by maintaining the water covered by boards during harvesting at the end of the growing cycle. Furthermore, the water cooling system can be designed to be
reversible and perform air heating in winter time, with the aim of extending the growing period. The
amount of heating power required by the heating system in winter time is thus estimated.
This study describes the thermal modeling of a novel algal biofilm photobioreactor aimed at cultivating algae for biofuel production. The thermal model is developed to assess the photo-bioreactor’s thermal profile and evaporative water loss rate for a range of environmental parameters, including relative humidity, ambient air temperature, solar irradiation, and wind speed. First, a 24 hour simulation of the system has been performed using environmental data for Memphis, TN, USA on a typical spring day to assess the diurnal variations in system performance. Then, a sensitivity analysis is performed to assess the effect of each environmental parameter on the temperature and evaporative losses of the photobioreactor. It is observed that because of the high surface area-to-volume ratio of the system, the temperature of the system exceeds that of the maximum ambient temperature during daylight hours by approximately 0.5 °C and is lower than the minimum ambient temperature at night by approximately 1.4 °C because of evaporative and radiative cooling. Furthermore, without active cooling, the characteristic evaporative water loss from the system is approximately 4.8 L/m2 -day.
Tilapia has been named as the 'food fish of the 21st century' and has become the most important farmed fish. China is the world leader in tilapia production and export. Identifying information and functional requirements is critical in developing an efficient traceability system because traceability has become a fundamental prerequisite for exporting aquaculture products.
This paper examines the export-oriented tilapia chains and information flow in the chains, and identifies the key actors, information requirements and information-capturing points. Unified Modeling Language (UML) technology is adopted to describe the information and functionality requirement for chain traceability. The barriers of traceability system adoption are also identified.
The results show that the traceability data consist of four categories that must be recorded by each link in the chain. The functionality requirement is classified into four categories from the fundamental information record to decisive quality control; the top three barriers to the traceability system adoption are: high costs of implementing the system, lack of experienced and professional staff; and low level of government involvement and support.
The general problem of heat exchange, including heat exchanger design, heat conduction analysis, convective heat transfer, and thermal radiation are discussed. (N.G.G.)
A transient analytical model is presented to study the effectiveness of an even shape greenhouse used for heating the aquaculture pond during extreme winters. The model was solved for the climatic conditions of Delhi (Latitude: 28°35′N), representing the northern India (comprising the states of Haryana, Punjab, Uttarakhand and Himachal Padesh) for the typical day (20th January) of winter. A simple trapezoidal design of aquaculture pond is proposed. Parametric studies involved the effects of length, breadth, depth, inclination of lining of fishpond, depth of water and air change in the greenhouse on the water heating in the fishpond. The performance of fishpond was assessed in terms of temperature gain, mean thermal efficiency and thermal load leveling. The optimum parameters for fishpond were 30 m length, 16 m breadth, 1.25 m depth, 1.0 m water depth, 75° lining inclination, and 8 air changes per hour for maximum temperature gain, maximum thermal efficiency and minimum thermal load leveling. A 20 °C rise in water temperature could be achieved during the day and 11 °C in the month of January. The maximum heat gain and loss are at around 16:00 and 7:00 h of the days, respectively.
Results are described of a study of employing the abundant solar energy of the arid central regions of South Africa for heating outdoor recirculating wintering pools for the fish Oreochromis mossambicus, which cannot tolerate water temperatures below 10 degree C. A standard, transparent swimming pool 'solar blanket' was suspended over the top of each fish pond, and two of the ponds were also connected to 10m**2 solar panels. The minimum water temperature never dropped below 12 degree C in the plastic-covered ponds and below 13 degree C in the ponds with plastic covering and solar panels.
This paper describes a computer-based method of modelling the transient performance of greenhouses. The method was developed to assist in the design of low energy protected cropping structures to be used in the hot, arid inland climates of Australia. Because of the generalized form it has applicability to a wide range of climatic conditions.To facilitate the modelling procedure, a greenhouse is considered to be composed of a number of separate but interactive components. These are the cover, floor, growing medium, air space and crop. A particular feature is the use of a tomato crop model which responds to photo-synthetically active radiation, leaf temperature and CO2 level. Design criteria were that the greenhouses should use only a small amount of conventional energy for heating when necessary and that they must operate at all times in an essentially sealed condition for continuous CO2 enrichment. To satisfy the first criterion, solar air heaters, a rockpile thermal store and a moveable thermal screen were incorporated in the simulation model, while the second condition was met by simulating the performance of a total enthalpy wheel and evaporative cooler which dehumidifies and cools without ambient venting of the greenhouse.The paper presents details of the mathematical models of each component and lists the assumptions used with each. The simulated performances of a number of different greenhouse types in winter and summer are presented and an analysis of the simulated crop yields, energy flows and temperatures indicates that the model is simulating the expected trends in greenhouses.
A pond heat and temperature regulation (PHATR) model was designed to: (1) predict the temperature for earthen outdoor aquaculture ponds and (2) determine the size of energy transfer mechanisms affecting energy gains or losses for these ponds. The model solves a first order, no-linear differential equation using a 4th order Runge-Kutta numerical method and various input data (weather data, pond characteristics and flow rate data). Output data (predicted pond temperature) was compared to measured pond temperature collected from the warmwater ponds at the Louisiana State University Agricultural Center Aquaculture Research Station, Baton Rouge, Louisiana. The model over-predicted the temperature for unheated ponds by 0.7 °C and for heated ponds by 2.6 °C. Fluctuations in flowrates of warm water used to heat the pond are believed to be responsible for the greater error in predicting heated pond temperatures. On average, the two most important energy vectors for unheated ponds were longwave pond radiation (39%) and longwave sky radiation (31%). At certain times, solar radiation accounted for as much as 49% of all energy transferred to unheated ponds. For heated ponds, on average, important energy transfer mechanisms were longwave pond radiation (25%), longwave sky radiation (19%), warm geothermal-well water (19%) and discharged water (15%). At certain times, solar radiation accounted for as much as 50% and warm well water 60% of all energy transferred to heated ponds.
Economic viability of fish production in a recirculating aquaculture system (RAS) facility depends, in part, on minimizing the energy requirements of operating such facilities. A step-wise, steady-state thermal model was developed to simulate the RAS thermal environment and energy expenditure for heating, ventilation, water pumping, biofilter operation, and lighting over a production cycle. The model was validated using temperature and energy data collected from the RAS facility of Virginia Tech during 1992. Simulations were performed with various production scenarios. Heating makeup water and the building required the most energy (40–70% of total), followed by water pumping, biofilter operation, lighting, and ventilation. The heating energy requirement of the facility increased with an increase in either fish stocking density or wastewater discharge from the facility due to increased heat loss through water replacement. However, the energy cost of production ($/kg) was the lowest for high stocking-density production scenario. Heat recovery from discharged wastewater is recommended to reduce the energy cost of fish production in RAS.
Analysis of the observations of long-wave radiation from clear skies, R, made by Dines at Benson, yields a correlation coefficient of 0·99 between R and the black-body radiation at the corresponding screen temperature T. A new series of measurements over wider ranges of temperature and humidity confirms this, with the same value for the correlation between R and σT4, the regression equation being: R = −17·195 σT4 (milliwatt cm−, T °K).
An alterlative representation of equals accuracy is R = 5·31.10−14 T−6 (Milliwatt cm−2, T°K) The latter formulation is probably better founded physically, and brings out the temperature dependence of the ‘effective emissivity’ ϵ (i.e. R/σT4), which the atmosphere must exhibit. Either expression provides an estimate of R in terms of T with a probable error less than 0·5 mw cm−2.
The present analysis omits any explicit reference to the influence of vapour pressure e on R, and so differs essentially from those due to Brunt and Angström. Re-appraisal of these latter suggests that the relationships established therein between * and e result basically from a correlation between temperature and humidity. Both the nature and the degree of the correlation between RσT4 and e for a given locality would then depend on the temperature-humidity regime occurring there. The wide variations from place to place, both in the values of the coefficients occurring in the Brunt and Angström equations, and in the degree of correlation found between R/σT4 and the corresponding function of e, are thereby explained.
A method for in-situ thermal calibration of unventilated greenhouses is proposed. The model whose coefficients are to be evaluated is: where the five terms represent: (1) the heat from the heater, (2) the heat generated by solar radiation (So), (3) the rate of heat storage in the system, (with dTm/dt representing the rate of change of the thermal mass temperature), (4) the loss by convection and infiltration due to the temperature difference (Ti−To) between the inside and the outside, and (5) radiation through the cover.The parameters to be evaluated are U, the overall heat transfer coefficient; a, the heating efficiency of the solar radiation; C, the heat capacity of the greenhouse; and R, a correction factor for radiative heat transfer. Latent heat transfer is not considered explicitly, but does affect the value of U.Experimental results for greenhouses at Technion and at Cornell University indicate that predicted values of the coefficients, in particular U and a, are consistent enough to be useful. The effect of heat capacity on the predictability of inside temperatures and system time constants should not be ignored. It presents, however, certain difficulties in application.A comparison between a dry and a wet greenhouse (both devoid of plants) showed that the heat transfer coefficient U for the wet greenhouse was higher by 28% than for the dry greenhouse. This is attributed to the latent heat contribution through the evaporation-condensation cycle and through infiltration.
This study describes the thermal modeling and its validation of greenhouse fish pond systems. Numerical computations have been performed for a typical day in the month of June, 2005, for the climatic condition of Champawat in the Central Himalayan Region. The energy balance equations have been written considering the effects of conduction, convection, radiation, evaporation and ventilation. The governing equations are numerically solved with Matlab 7.0 software to predict the water temperature. A parametric study has also been performed to find the effects of various parameters, namely the number of air changes per hour, the transmissivity (τ) and the isothermal mass and height of the greenhouse. It is observed that there is no significant effect in the parametric studies on water temperature due to the larger isothermal mass. The model has been validated with experimental data. On an average, the even span passive greenhouse fish pond can increase the inside temperature 4.14 °C higher than the temperature of an outdoor pond. Statistical analysis shows that the predicted and experimental values of water temperature exhibited fair agreement with a coefficient of correlation r = 0.90 and root mean square percent deviation e = 1.67%.
The literature over the past 25 years indicates that there has been a continued interest in using passive and active solar technologies to reduce the conventional energy required to maintain water temperatures in small recirculation aquaculture systems. Although all of the experimental systems reviewed report favourable results, there is little information available to guide system designers. This paper describes the use of a simulation model to predict the annual conventional energy consumption of a 10.6 m3 RAS enclosed in a double layer polyethylene greenhouse in two different climates. The water was maintained at 22.5 °C and the recirculation rate was 10% of tank volume per day. Simple unglazed solar collectors have also been combined with the greenhouse to further reduce energy consumption. The effect of increasing collector area on the solar fraction and utilization of useful energy was predicted. Finally, the model was used to investigate the relationship between the occurrence of condensation on the inner cover, ventilation rates and energy use.It was found that in a hot dry climate, the greenhouse alone was sufficient to reduce the conventional energy requirements by 87%; while in the cooler temperate climate reductions of 66% were possible. When solar collectors were added to the system, conventional energy requirements were reduced further and depended on the area of collector used. For example, in the temperate climate location, conventional energy requirements were reduced to 23% of a RAS enclosed in a non-solar building when 26 m2 of solar collector inclined at the optimum angle for winter energy collection were used. Although condensation could be successfully reduced by ventilation of the greenhouse, this increased conventional energy requirements because the potential for evaporation was increased. Covering the tanks at night was found to be a more effective strategy because it reduced condensation and conventional energy use simultaneously.
A model for fan-ventilated greenhouse cooling is presented in which the primary heat transfer surfaces (cover/structure, canopy and floor) are represented as three parallel planes. Validation of the model was accomplished using data collected over 14 days. Agreement was good, with canopy temperatures over-predicted by only 0·1%, air temperatures in the canopy under-predicted by 0·5%, humidity of the canopy air under-predicted by 1·6% and transpiration rates under-predicted by 1·4%. Simulation runs suggest that when evaporative pad cooling is not used, little advantage is derived from increasing airflow rates beyond about 0·05 m3 m−2 s−1. When evaporative pad cooling is used, however, both air and canopy temperatures decline with increasing airflow rates up to 0·13 m3 m−2 s−1, the highest level considered. Increasing canopy size is predicted to be more influential in reducing air temperatures when evaporative pad cooling is used than when it is not, but its effect on canopy temperature is expected to be approximately the same whether or not evaporative pad cooling is used. With no evaporative pad cooling, the evapotranspiration coefficient (i.e., the ratio of energy used for transpiration to incoming solar energy) is predicted to range from 1·75 for an outside temperature of 36·8°C and an outside humidity ratios of 3·3 g kg−1 to 0·8 for an outside humidity ratio of 29·9 g kg−1 at the same temperature. With evaporative pad cooling, the coefficient is predicted to range from 0·6 to 0·8 at the same outside temperature and the same range of outside humidity ratios.
A mathematical model to stimulate thermal stratification in shallow aquaculture ponds is described. The dynamic, mechanistic model was developed to simulate the water column of ponds in discrete, completely mixed, horizontal volume elements. Energy exchanges between the pond's surface and atmosphere were calculated with theoretical and empirical relationships commonly applied to heat balance calculations in lakes, reservoirs and waste treatment ponds. Energy transfer between the volume elements caused by turbulent mixing were simulated as functions of the temperature gradient in the water column and a diffusion coefficient. The value of the diffusion coefficient was calculated in each time step as a function of wind speed, depth, and the water column density gradient. The model was implemented using a dynamics simulation language (STELLA™) using an Apple Macintosh™ microcomputer. Also described are the model calibration and verification procedure and results.
Greenhouse pond systems (GPS) can provide a good alternative for maintaining water temperature in aquacultural facilities. However, their thermal characteristics are not well understood. The GPS model advanced in this paper describes the evolution of various heat and water vapor transfer fluxes, temperature and humidity at a given site under various climatic conditions. Simulation results show that, in a 1-m pond, a passive polyethylene GPS can yield a 5.2°C increase in water temperature compared with outside air temperature. The night temperature of the internal air in a passive GPS can be maintained a few degrees higher than that in a horticultural greenhouse. The main heat losses of the water in the GPS are thermal radiation to the cover, convection from the cover to the external air, and thermal radiation from the cover to the sky. Reducing these three heat flux densities is the principal measure for maintaining water temperature or saving energy in a GPS. Water condensation frequently occurs on the inner surface of the cover, which makes highly thermal-radiation-transparent covering materials like polyethylene become opaque to thermal radiation and behave like low emissivity glass. Polyethylene is thus a more sound material for the GPS cover than glass. Mean water temperature in a passive polyethylene GPS is 0.6°C higher than that in a glass GPS, while, in an active polyethylene GPS, the total heat demand is 9.2% lower than that in a glass GPS. From a temperature maintenance point of view, polyvinyl chloride is almost as effective as polyethylene. This model can provide a useful tool for optimum control of water temperature and evaluation of the economic potential for the active GPS.
The prediction of aquaculture pond temperatures throughout the year is essential to the design and evaluation of potential aquaculture sites. A site may obtain the necessary heat inputs from the sun, geothermal wells or industrial and power plant waste heat. The amount of heat addition necessary is dependent upon climatic and environmental factors at the site.The MAPT (Maintenance of Aquaculture Pond Temperatures) model was developed to determine the potential for warm water aquaculture at any site in the world. Hot water sources and solar radiation provided the heat inputs to the model while the heats of evaporation, convection and radiation were responsible for the heat losses.The model was used to consider a variety of heat loss reduction methods, heat transfer methods and projected the pond temperatures and animal production rates. It has been applied to several sites around the world and provides an inexpensive means for evaluation of production potential without extensive site data collection.
A method has been developed to determine experimentally in situ the convective heat transfer coefficients on the inside and outside of the greenhouse cover. The method is based on the energy balance of the greenhouse cover and it was applied to a small experimental polyethylene covered greenhouse. The convective heat transfer coefficients on the inside and outside of the cover were determined as functions of the air-cover temperature difference and the air velocity inside the greenhouse, as well as the wind velocity outside the greenhouse. Also, the nature of the convective heat transfer at the outside and the inside of the greenhouse cover was investigated. At the outside of the cover at moderate wind velocities mixed convection is the prevailing convective heat transfer mechanism. The convection heat transfer on the inside of the greenhouse cover is always pure free convection when the greenhouse vents are closed and the air velocity in the house is low. When the vents are opened the nature of the convection heat transfer depends on the air velocity in the house. Criteria are given to determine whether pure free, mixed or pure forced convection takes place.
Transpirational Cooling of Greenhouse Crops
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User's Manual for TMY2s Mixed, forced and free-convection heat-transfer at the greenhouse cover
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