Article

Performance analysis of a new type desalination unit of heat pump with humidification and dehumidification

Institute of Air-Conditioning & Solar Energy, School of Dynamics and Energy, Northwestern Polytechnical University, Xi'an, ShaanXi, 710072, China
Desalination (Impact Factor: 3.76). 03/2008; 220(1-3):531-537. DOI: 10.1016/j.desal.2007.01.053

ABSTRACT

Desalination with humidification and dehumidification process is deemed as an efficient and promising means of utilizing the condenser and evaporator of heat pump to produce freshwater from seawater. This paper presents a new type desalination unit driven by mechanical vapor compression pump which was designed and fabricated by the Institute of Air-Conditioning & Solar Energy of the Northwestern Polytechnical University. The unit utilized the heat from condenser and the cold from evaporator of heat pump adequately, and reclaimed most latent heat. The air, firstly, was humidified in the humidifier with the alveolate structure, and then was cooled in the precondenser and the evaporative condenser to produce freshwater. A mathematical model of the unit is presented, in which the hydrokinetics method was used to study the flow and the heat and mass transfer inside the alveolate humidifier. The effects of some of the operation such as flow rates, temperatures of cooling water and air, and etc., were studied in detail. The comparison between the numerical and experimental results was accepted. The desalination unit that is considered in the study produces freshwater 60 kg/day with the less electric power that is 500W and is proven to be an efficient desalination device to obtain freshwater.

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Available from: Penghui Gao, Feb 20, 2015
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    • "This study used the hydrokinetics method for the mathematical modeling of the desalination unit. The desalination unit produced 60 kg/d of freshwater with low electric power consumption of 500 W and has been validated to be an efficient desalination system for freshwater production, especially in remote area[89]. In traditional water-heated HDH, the thermal energy consumption is about 950 kJ/kg and the electrical energy consumption is about 5–18 kJ/ kg with a GOR equivalent to 2. Whereas for a mechanical compression HDH, no thermal energy is consumed, the electrical energy consumption is about 160 kJ/kg, and a higher GOR value of 6 and above can be achieved[67]. "
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    ABSTRACT: One of the innovative methods for decentralized low-scale purification of water is the humidification dehumidification (HDH) desalination technology. Many research activities have been carried out recently with the aim of improving this technology. The economic and environmental benefits of the HDH technology are enormous including feasibility of being powered by sustainable energy sources such as solar and geothermal, ability to operate at low temperature, low maintenance requirements, and simple construction needs. The principal HDH components, latest research on HDH systems driven by renewable energy, and recent innovations on HDH design for sustainable water production are discussed in this paper. It is worth noting that the development of the key features and sustainability aspects of HDH desalination technology are still under research and more improvements are needed to optimize process performance parameters in terms of quantity of water produced, specific renewable energy required, and specific cost of water produced. However, HDH technology has been proven to be an inexpensive and reliable desalination system in terms of environmental friendliness for small scale applications.
    Full-text · Article · May 2016 · Renewable and Sustainable Energy Reviews
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    • "c o m / l o c a t e / e n c o n m a n Yuan et al. [8] presented an integrative unit for air-conditioning and desalination driven by vapor compression heat pump on basis of direct humidification–dehumidification process. The performance of a new type of a humidification–dehumidification desalination unit driven by mechanical vapor compression heat pump using mathematical model to study the flow and heat and mass transfer inside the humidifier was analyzed by Gao et al. [9]. Wu et al. [10] analyzed theoretically the heat and mass transfer between air and water film in the direct evaporative cooler. "
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    ABSTRACT: Performance of integrative air-conditioning (A/C) and humidification–dehumidification desalination systems proposed for hot and dry climatic regions is theoretically investigated. The proposed systems aim to energy saving and systems utilization in fresh water production. Four systems with evaporative cooler and heat recovery units located at different locations are proposed, analyzed and evaluated at different operating parameters (fresh air ratio, supply air temperature and outside air wet bulb temperature). Other two basic systems are used as reference systems in proposed systems assessment. Fresh water production rate, A/C cooling capacity, A/C electrical power consumption, saving in power consumptions and total cost saving (TCS) parameters are used for systems evaluations and comparisons. The results show that (i) the fresh water production rates of the proposed systems increase with increasing fresh air ratio, supply air temperature and outdoor wet bulb temperature, (ii) powers saving of the proposed systems increase with increasing fresh air ratio and supply air temperature and decreasing of the outdoor air wet bulb temperature, (iii) locating the evaporative cooling after the fresh air mixing remarkably increases water production rate, and (vi) incorporating heat recovery in the air conditioning systems with evaporative cooling may adversely affect both of the water production rate and the total cost saving of the system. Comparison study has been presented to identify systems configurations that have the highest fresh water production rate, highest power saving and highest total cost saving. Numerical correlations for fresh water production rate and total system energy consumption are developed and presented in terms of the controlling parameters.
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    • "Al-Juwayhel et al. [6] used a combined vapor compression heat pump with a single effect evaporator desalination system for atmospheric water vapor condensation on the evaporator surface. The performance of a new type of a humidification– dehumidification desalination unit driven by mechanical vapor compression pump was mathematically analyzed by Gao et al. [7]. Yuan et al. [8] presented an integrative unit for air-conditioning and desalination driven by vapor compression heat pump on basis of direct humidification–dehumidification process. "
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    ABSTRACT: An experimental study of the performance of a hybrid humidification–dehumidification water desalination and air conditioning system using vapor compression refrigeration cycle is presented and investigated. A test rig is designed and constructed to study the performance under different operating parameters (air flow rate, air inlet temperature, specific humidity and evaporator saturation temperature). The effects of these operating parameters on fresh (desalinated) water production rate, refrigeration capacity, compressor work per kilogram of fresh water, mass transfer coefficient and supply air conditions to conditioned space (air temperature and relative humidity) are investigated and analyzed. The results show the enhancement of the fresh water production rate, the refrigeration capacity and the compressor work per kilogram of fresh water with increasing air specific humidity and air mass flow rate. The supply air temperature and relative humidity increase remarkably with increasing fresh water rate. Experimental correlations for fresh water production rate, refrigeration capacity and compressor work per kilogram of fresh water in terms of all studied parameters are deduced and presented within accepted error.
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