Atsushi AkisawaTokyo University of Agriculture and Technology | TUAT · Graduate School of Bio-Applications and Systems Engineering (BASE)
Atsushi Akisawa
Doctor of Engineering
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351
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Introduction
Adsorption refrigeration cycles, utilization of wasted heat,
solar concentrators and the application for solar thermal use, solar cooling system and
optimization model analysis of distributed energy systems such as CHP.
Additional affiliations
April 2000 - present
Publications
Publications (351)
This study focuses on solid oxide fuel cell (SOFC) co-generation systems for commercial buildings. The objectives of this study are to investigate the potentials of SOFC installation into various commercial buildings under regional conditions, and to estimate geographical distribution of SOFC potentials over Japan. An optimization model minimizing...
The compound parabolic concentrator (CPC) is a core technology in the field of solar concentration. Nevertheless, it only has one degree of freedom in the choice of its half-acceptance angle. In this study, extending the idea of the three-dimensional CPC, a design method for new kinds of concentrators having a CPC shape at each profile with various...
The objective of this study is to build an optimization model expressing the supply chain of wooden fuels from thinning to users. The whole supply chain is optimized in terms of the total economic cost to control thinning, selling, transportation, drying, processing, storage, and supply to the demand side. The model incorporates selling thinned woo...
In this study, it is assumed that solar thermal collectors will be installed on the wall of houses so that photo voltaic facilities can be set on the roof because of the wide area requirement. The objective of this study is to focus on a vertically installed solar concentrator with mirrors designed in the previous research, and to measure its sunli...
It was reported that acoustic wave enhanced the adsorption speed of Silica gel by experiments and low frequency oscillating flow also would enhance the adsorption speed by CFD simulations. The objective of this study is to construct low frequency oscillating flow generator and to confirm the effect of the oscillating flow on the adsorption. Two blo...
This study investigates the performance of double effect adsorption refrigeration cycle that utilizes the adsorption heat of a high-temperature adsorbent heat exchanger for desorption of a low-temperature one. Because there is a freedom to select an adsorbent for each adsorbent heat exchanger, the combination of adsorbents such as silica gel, FAM-Z...
This study investigates the additional installation of a high-speed diesel generator to independent microgrids (MG) such as remote islands where relatively efficient medium-speed diesel generators (DGs) are mainly used. While small-sized and lightweight, high-speed DGs are not widely spread for continuous usage because their efficiency is lower tha...
Recently, the introduction of renewable energy, especially Photovoltaic power generation (PV), has been increasing. On the other hand, it has been pointed out that there might be lack of adjustment capability in the grid system. As a countermeasure, Demand Response (DR) is expected to contribute to the adjustment of supply and demand. The objective...
There is a method of using porous media to improve the heat transfer performance of the heat tube. However, there are few studies on the fiber structure, which is one of the porous structures. Furthermore, by sintering the heat transfer tube and the porous media, the thermal resistance can be significantly reduced and the heat transfer can be expec...
Electric vehicles (EVs) and vehicle-to-home (V2H) technologies are expected to be used as domestic electricity storage systems, thereby promoting the self-consumption of photovoltaic (PV) power. The purpose of this study was to evaluate the profitability of V2H installation, the optimal facility configuration and the energy performance of V2H, whil...
In order to enhance the heat transfer performance of heat tubes, porous media are often sintered into them. This increases the heat transfer area due to the surface area being increased by the porous media. Our The test apparatus consisted of a double tube structure, and the length was 150 mm. Previous experiments have shown its usefulness and reve...
Combined cooling, heat and power supply systems (CCHP) are expected as a method of efficient use of energy, and gas engines are installed for power and heat supply for them in many cases of District heat and power supply (DHC). Conventionally, it presupposed that the same type of multiple gas engines is installed in a site, and considering the term...
In this study, refrigerant R134a experiments were carried out to observe two-phase flow in an oscillating horizontal rectangular minichannel conduit at refrigerant mass flux of approximately 30 kg•m⁻²•s⁻¹ to 300 kg•m⁻²•s⁻¹, saturation temperature of approximately 30°C, and average vapor quality in the test section inlet of approximately 0.05 to 0.9...
In this study, a wall mounted solar concentrating collector with parabolic and involute mirrors combined with an evacuated glass tube is designed to boost the solar energy collection for domestic hot water supply during winter. To optimize the device, the mirrors parameters are varied, and the amount of collected energy in each case compared throug...
A multistage thermoacoustic engine is composed of some regenerators sandwiched by heat exchangers, a waveguide, and its performance depends on the design parameters of each component. Therefore, to obtain high efficiency, we must simultaneously optimize the several numbers of the design parameters. In this study, we couple thermoacoustic theory and...
Recently thermoacoustic engine is being used to recover latent and sensible heat. However, the heat exchanger which is loaded by thermoacoustic engine has low performance because of large thermal resistance of the gas side. The purpose of this study is improving heat exchanger equipped with sintered fiber metal porous materials into the pipes in or...
This study focuses on the phenomenon that the adsorption speed is improved by acoustic wave. An experimental study reported the velocity amplitude of acoustic wave is closely related to the adsorption acceleration. The purpose of this study is to elucidate the adsorption acceleration phenomenon by CFD analysis. A model representing a packed bed was...
This study focuses on a thermo-acoustic engine which utilizes cold energy of LNG. The authors developed an experimental engine driven with liquified N2, which successfully generated acoustic power more than 100W. The objective of this study is to find an application of thermo-acoustic engine combined with conventional propane cycle for LNG power ge...
This study was focused on the evaluation of the adsorption kinetics of water vapor onto silica-gel with and without an acoustic field, in an objective to reveal the enhancement mechanisms of water vapor adsorption by an acoustic wave. Adsorption uptake curves of water vapor from humidified air onto the silica-gel with and without acoustic field wer...
Data centers use 40 percent of the total electricity consumption for cooling servers. The objective of this study is to make simulation models to analyze the performance of a heat pump system which utilizes the waste heat of servers for hot water supply. It was predicted that the COP of the heat pump system would be 5~6 when it produces hot water o...
The authors found that acoustic wave enhanced the adsorption speed of Silica gel under atmospheric pressure. It is interesting to know whether the adsorption enhancement occurs in low pressure conditions because adsorption chillers work at very low pressure of refrigerant. The objective of this study is to investigate the effect of acoustic wave in...
Co-generation system is installed for District Energy supply systems in many cases, and the economic feasibility is not generally investigated in consideration of its failures, but the impact of failure is not small since Co-generation system usually covers power, heating and cooling supply. Therefore, the objective of this study is to investigate...
This study focuses on the solid oxide fuel cell (SOFC) cogeneration system for commercial buildings. SOFCs are considered to be suitable for buildings with low thermal demand because of the high power generation efficiency. The objective of this study is to analyze the effects of SOFC installation into various commercial buildings from energy savin...
Liquefied Natural Gas (LNG) is becoming vital in relation to energy transition and fighting climate change. Because of its cryogenic temperature (111 K), LNG is an exergy “mine” that can be exploited in the regasification process for multiple industrial applications. But this exergy is usually wasted.
This research presents a Combined Cold and Powe...
Liquefied Natural Gas (LNG) is a valuable exergetic source due to its low-temperature (−162 °C). However, LNG is regasified using seawater as heat source and without exergy recovery in most of LNG terminals worldwide. In this paper we model a polygeneration plant that recovers the low-temperature and pressure exergy from LNG-regasification to gener...
The thermoacoustic engine that can be driven by cold exergy has been designed and constructed. It is composed of a looped tube, a straight tube, two heat exchangers, a regenerator, and a tank. The regenerator is sandwiched by the heat exchangers and is located in the looped tube. When the temperature ratio of the heat exchangers exceeds 1.7, the ga...
The objective of this study is to construct mathematical expressions to estimate the optimum cycle time which maximizes the specific cooling power (SCP) of adsorption chillers with silica gel-water pair. The operating temperature conditions of hot water, cooling water and chilled water, as well as the design parameters such as heat transfer coeffic...
In this study the enhancement effect of adsorption mass transfer by acoustic wave is investigated to understand how the acoustic wave influences the adsorption performance. The experimental data were obtained to show the behavior of silica-gel adsorption with/without acoustic field. The experimental results showed the adsorption speed with acoustic...
The temperature of waste heat from a data center is about 40°C. The waste heat is not reused and thrown away. It is important to use it for other facility. The objective of this study is to build an optimum operation model to balance supply and demand of energy. The system consists of a heat pump, a hot water tank and tap water. Waste heat from the...
There is a cogeneration system(CGS) as a method of efficient use of energy. The overall efficiency of the CGS is 70 to 85%, but there is a problem that the total efficiency is influenced by other equipment making up the system. In this research, we focus on gas engines among equipment. Gas engines are divided into high speed type and middle speed t...
This paper presents static analyses of two stage adsorption cycle using FAM Z01 & FAM Z05 as the adsorbents. The conventional two stage system consists of four adsorbent beds. In contrast, in new scheme three beds were used assigning FAM Z01 and FAM Z05 combination for low and high pressure sides, respectively. The objectives of this study were to...
The utilization of waste heat instead of fuel combustion is effective in reducing primary energy consumption to mitigate global warming problems. As waste heat sources are not necessarily located close to areas of heat demand, one of the difficulties is that waste heat must be transferred from the heat source side to the heat demand side, which may...
A system which is driven by low-grade heat around 60–90 °C is expected to enhance the use of the solar heat and waste heat. The adsorption refrigeration is capable of operating at low-grade heat while the challenge is how to increase the efficiency of current implementations of adsorption refrigerators. The double-effect cycles have higher COP than...
Recently PV systems combined with batteries are discussed to utilize renewable energy effectively. This paper focuses on residential community equipped with PV systems as well as batteries or electric vehicles (EV). The advantage of EVs is the affordable cost of battery compared with home batteries. On the other hand, EVs do not work as batteries w...
In order to improve the efficiency of adsorption refrigeration cycles, this study proposes a triple-effect adsorption refrigeration cycle equipped with a compressor. The compressor has a role to adjust the pressure of adsorption process in order to expand the range of adsorbent concentration. The objective of this study is to evaluate the effect of...
The authors proposed “Solution Transportation Absorption Chiller” which is driven by wasted heat and transfers absorbent solution instead of chilled water. It consists of generator-condenser pair on the heat source side, absorber-evaporator pair on the demand side and pipelines between them. In this study, the authors investigated the heat transpor...
In order to improve the efficiency of the adsorption refrigeration cycle, this study proposes a triple-effect adsorption refrigeration cycle equipped with a compressor. This cycle can run in order to create a large variation in adsorbent concentration range by the compressor, even if there is little temperature variation in the desorption and adsor...
The objective of this study is to evaluate the performance of the solar chimney installed in the warehouse by variation of directions and to visualize the air flow in the warehouse. The objective crop is orange in this study. The air flow rate inside the solar chimney increases by stack effect. The solar chimney is installed in 30 degree intervals...
This study focuses on solid oxide fuel cell (SOFC) for commercial buildings. Although SOFCs have high power generation efficiency, it was predicted that SOFCs would not be adapted by buildings with low thermal demand such as office buildings. The objective of this study is to investigate the environmental and economic effects using optimization mod...
The objectives of this study are to design a mirror concentration system with an evacuated tube heat collector installed on walls and to evaluate its performance. The proposed system consists of a parabolic mirror combined with an involute curved mirror and an evacuated tube. Ray tracing simulation was employed to evaluate the performance of collec...
This study estimates the performance of a single stage adsorption heat pump by collecting adsorption and condensation heat for hot water supply in winter. The adsorption heat pump gains heat from cooling water that circulates in the adsorber during the adsorption process and the condenser. Silica-gel is chosen for the adsorbent. Chilled water in th...
This study examined the performance of a photovoltaic system with flat mirrors and south-to-north direction sun tracking system. The proposed system is composed of flat mirrors and solar cells connected each other alternately, which can track the sun by expansion and contraction. The objectives are to find out the optimum operation of the inclinati...
The objective of this study is to optimize the design of thermoacoustic engines driven by LNG in order to exploit its unused energy at low temperature. LNG at 111K provides low temperature heat source while the environment has a role of high temperature heat source. The design variables such as regenerator channel radius, regenerator length, regene...
This study investigates the effect of operating temperature on the optimum cycle time of adsorption chillers maximizing the specific cooling power (SCP). The objective is to construct an experimental expression to determine the optimum cycle time at each operating temperature. Silica gel-water pair was chosen as the adsorbent-adsorbate combination...
When failure occurred in the district heating and cooling with Co-Generation system, the installation of backup facilities is necessary. Moreover, there will be the cost due to power failure. It is assumed that the cost has an influence on constitution and the economy of the system. In this study, evaluation for district heating and cooling conside...
Adsorption chillers are expected as an effective utilization of the low temperature exhaust heat. The purpose of this study is modeling single stage adsorption chiller using MATLAB/Simulink and simulating cooling capacity with heat source temperature fluctuation. Heat source temperature was given as a sine function, and its amplitude and period wer...
The objective of this study is to investigate users' preference for solar water heaters which are regarded as effective measures to reduce fuel consumption in houses. A questionnaire survey was conducted over whole Japan to collect 2500 samples. The survey result was analyzed from the viewpoint of the interest in solar water heaters. It was found t...
An oscillating steam engine has been expected as a low cost and efficient energy conversion system at a low operating temperature. In this study,we numerically investigate the oscillating steam engine . It was found, when the total volume of the engine is 4.5cc and hot section is 60mm , it can produce 18.9w. This result is able to reproduce the out...
The objective of this study is to evaluate the performance of the solar chimney installed in the warehouse by variation of directions. The airflow rate inside the solar chimney increases by stack effect. The solar chimney is installed in 30 degree intervals from the East to the West. A year thermal energy collection of the solar chimney tilted 30 d...
The objective of this study is to evaluate the performance of SOFC (Solid oxide fuel cell) installed in office or hospital buildings. The higher efficiency of power generation is considered advantageous for electricity oriented users in commercial sector. Optimization model to minimize the system cost with co-generation was employed to analyze how...
The objective of this study is to examine proposed 2 stage adsorption refrigeration cycle consisting of 3 beds experimentally with hot water of 60 degC and cooling water of 30 degC. Low pressure side is running in the same way as conventional 2 stage cycle while high pressure side is operated twice as quickly as the low pressure cycle. It was confi...
An oscillating steam engine has been expected as a low cost and efficient energy conversion system at a low operating temperature. The previous study reported that thermal efficiency increases with decreasing the temperature difference between the cooling and heating sections. However, this result does not agree with the dependence of a general hea...
The objective of this study is to evaluate the power generation performance of the axial flow propeller turbine, and ascertained that effective as a micro-hydroelectric power propeller in conditions of low-drop (drop the number of 1-5m) and small flow (Flow rate 0.1 ㎥/s or less). Further, we propose a micro-hydropower generation systems that combin...
In this study, we performed to observe horizontal vapor-liquid two phase flow of refrigerant R 134a in the rectangular glass channel which hydraulic diameter is 0.84 mm. The test glass tube was added the oscillation to the gravity direction for slug and stratified flow under low mass flux and heat flux. When the channel was oscillated of certain fr...
The onset temperature of the thermoacoustic engine is required to bring down in respect of utilizing waste heat. Tsuda reported that the onset temperature is 343K when water vapor exist in the thermoacoustic engine. However it does not investigate the influence that adding water vapor gives in the temperature distribution in the stack of the thermo...
The oscillating heat pipe (OHP) has attracted attention due to its high efficient transportation. We aim to enhance heat transport performance of this attracting device by adding vibration. Our experimental apparatus is made of OHP and Vibrator. OHP is mainly made of glass tube for visualization and it has 5 turns. We measured effective thermal con...
A thermoacoustic refrigerator is the apparatus in which an acoustic wave contributes to the heat pumping. A conventional thermoacoustic refrigerator consists of a resonance tube, a stack, and two heat exchangers. To improve the limitation of performance of this refrigerator, a multistage thermoacoustic refrigerator is proposed and numerically analy...
A thermoacoustic electric generator is a device for power conversion from heat into electricity. The device typically consists of a thermoacoustic engine and a linear alternator. Linear alternator has a high efficiency, whereas it has an inherent disadvantage in upscaling. Therefore, De Blok et al. proposed using bi-directional turbines. Referring...
Using audio speaker with thermoacoustic engine, we can get electricity from heat. This type of thermoacoustic devices are called thermoacoustic electric generator. In this paper, the character of an audio speaker is studied and the calculation model for the numerical calculation is made. The calculation of the multi-stage looped tube thermoacoustic...
This article presents the design and the heat transfer study in a novel adsorbent bed with compound parabolic concentrator (CPC) for solar adsorption chillers. The objectives of the study were to investigate the heat transfer in the adsorbent bed experimentally, and to verify the fins layout through finite-element analysis (FEA) simulation. CPCs wi...
This study investigated the cycle optimization of four-bed, silica gel–water adsorption with reheat cycle, where the desorber (upper bed) and adsorber (lower bed) always interact with the condenser and evaporator, to exploit a low heat-source temperature. In a previous study, the performance of a reheat cycle with chilled water outlet temperature f...
This study examined the performance of a solar collector with a parabolic mirror mounted vertically on walls. In order to simplify the system, in does not have sun tracking function and focuses on hot water supply only during winter which dominates heat demand. The objectives are to design the parabolic concentrator by simulations and to demonstrat...
The objective of this study is to evaluate the performance of SOFC (Solid oxide fuel cell) installed in office buildings. The higher efficiency of power generation is considered advantageous for electricity oriented users like offices in commercial sector. Optimization model to minimize the system cost with co-generation was employed to analyze how...
The authors have examined heat transportation based on ammonia absorption cycle named STA. STA recovers discharged heat and converts it into cooling. New type of STA was proposed in this study, which incorporates two evaporators to provide cooling at different temperature simultaneously. The objectives of this study are to investigate the static pe...
The objective of this study is to investigate the performance of double effect adsorption cycles with various adsorbents. Double effect cycles have higher COP than conventional single stage adsorption cycles. Two types of double effect cycle were examined by means of static cycle simulation assuming equilibrium states where the cooling effect is do...
The adsorption refrigeration chiller is environmentally friendly because of the use of a natural refrigerant and the use of a low-grade thermal energy as the driving energy source. In this paper, an experimental investigation of a reheating two-stage adsorption chiller was conducted, and the working principle of the cycle was also introduced. The c...
A water Stirling engine has attracted attention because it can work without any moving parts and can use variety of heat sources. This device was composed of a tube containing a regenerator; the regenerator consisted of many narrow flow channels. We built a multistage water Stirling engine and measured the oscillation temperature and the pressure a...
The steam engine that is essentially same to the Pop-pop boat engine has been experimentally investigated. In this study, we measured P-V diagram and input power to the heater of some rotation speeds, and confirmed that output power was 4.0W and thermal efficiency was 1.3% under the conditions that rotation speed was 180rpm and the temperatures of...
This paper presents the application of The Particle Swarm Optimization (PSO) for the design of a thermoacoustic device. As a thermoacoustic device, a traveling wave thermoacoustic refrigerator with a branched tube is employed and the three parameters, regenerator's radius, position, and length, were optimized. The obtained results are compared with...
A thermoacoustic electric generator is a device for converting heat into electric power via acoustic power. In this study, we have focused on the method to convert acoustic power into electric power and demonstrated the use of a bi-directional impulse turbine. We manufactured the impulse turbine and connected it to a motor. The turbine is located i...
The objective of this study is to investigate the technological feasibility of heat transportation based on ammonia absorption cycle named STA. STA recovers discharged steam from waste power generation to convert it into cooling and heating supply. An optimization model was employed to analyze technological selection wity the criteria of minimizing...
Solar adsorption refrigeration is promising technology especially in the developing countries and remote areas because the system can be driven by solar energy without involving electricity. Therefore, it is technologically possible and socially feasible in the areas where electricity is not enough but solar energy is rather easy to obtain. The con...
Energy-saving building (Zero Emission Center) was built in Koganei Campus of the Tokyo University of Agriculture and Technology as a NEDO project that aims at reducing carbon-dioxide emissions down to zero. Various energy-saving technologies such as solar energy equipments (solar collector, solar wall, etc.) are installed there. The objectives of t...
Solar heat collector is influenced by the change of the weather and seasons. So that the concentrated system necessary to this device. The objective of this paper is to evaluate the concentration performance of circular tube with internal prisms. This circular tube used evacuated tube collector is designed by nonimaging Fresnel lens. Ray tracing si...
Simulation study of heat transfer in an adsorption bed with CPC-shaped solar collector was carried out. The objectives of this study were to make a simulation model and verify it with experimental results, and to find the effect of fin pitch in heat transferring. The solar heat distribution on CPC receiver was obtained by ray tracing on CPC geometr...
Simulation study of a solar adsorption refrigeration system using a wing type compound parabolic concentrator (CPC) is presented. The system consists of the wing type collector set at optimum angles, adsorption bed, a condenser and a refrigerator. The wing type collector captures the solar energy efficiently in the morning and afternoon and provide...
The design and operation of a three-bed mass recovery silica gel water-based adsorption cooling cycle has been outlined along with the performance evaluation of the system. The system can operate in a dual mode, either single-stage mode or two-stage mode, without any change of its physical configuration. The cycle time of the system is optimized to...
This paper proposes a three-bed three-stage adsorption cycle with a new operational strategy. The cycle consists of three adsorber/desorber heat exchangers, one evaporator, and one condenser. The two beds on the low-pressure side operate in a reheat cycle, and another bed on the high-pressure side operates in a conventional cycle. The objectives of...
We designed a compound parabolic concentrator (CPC) with wings angled toward the east and west. Normally, solar collectors are straight, facing south, and the effective temperature is only achieved for a short period of time at midday. In the proposed design, the collector is divided into three parts, with the ends angled and tilted at different or...
We measure the temperature required to drive a thermoacoustic engine and compare containing only air with containing air, water vapor, and liquid water as the working fluids. The oscillation temperature in the case of containing dry air is measured to be 134℃ whereas in the case of containing wet air is measured to be 67℃. Moreover, the results of...
A water desalination system includes an evaporator for evaporating saline water to produce water vapor and an adsorption means in selective vapor communication with the evaporator for reversibly adsorbing the water vapor from the evaporator. The adsorption means is in selective vapor communication with a condenser, and desorbing means for desorbing...
This article presents the optimal cycle time and performance of two different types of silica gel–water-based three-bed adsorption chillers employing mass recovery with heating/cooling scheme. A new simulation program has been developed to analyze the effect of cycle time precisely on the performance of the systems. The particle swarm optimization...
This paper aims at designing a simplified method to estimate the potentials of photovoltaic systems and solar water heaters in municipal scale based on public statistics. The method consists of three st eps: calculating energy demand in households, investigating potentials of the solar energy technologies and estimating the effect on primary energy...
Ammonia-water absorption refrigeration cycle converts thermal energy input into concentration difference of the refrigerant in solutions, then produces cooling. In the proposed system, refrigerant weak solution and strong solution are separately stored in tanks, which works as heat storage. This study investigated the feasibility of solution storag...
The objective of this research is to improve efficiency of conventional evacuated solar collector by simulation. To achieve this, the upper half of vacuum tube consists of Non-imaging Fresnel lens. Non-imaging Fresnel lens consists of many prisms and has acceptable half-angle. The vacuum tube is designed by changing parameters, for example, a posit...
A thermoacoustic heat pump can have high reliability and long lifetime because it has no-moving parts at a heating section. In this study, a thermoacoustic heat pump consisting of a linear motor, looped tube and brunch tube was constructed Working gas was nitrogen whose mean pressure was 0.5 M