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Xiaosong Zhang - One of the best experts on this subject based on the ideXlab platform.
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Experimental study on Liquid Desiccant regeneration by photovoltaic electrodialysis
Energy Procedia, 2019Co-Authors: Xiaosong ZhangAbstract:Abstract Liquid Desiccant regeneration is an important part of Liquid Desiccant air conditioning system and consumes the majority of the system’s power. Conventional methods for Liquid Desiccant regeneration use thermal energy to regenerate the Liquid Desiccant. One of the biggest problems for thermal regeneration is that the Liquid Desiccant should be cooled down before dehumidification. Furthermore, the efficiency for Liquid Desiccant regeneration drops under high temperature and humidity climates. In comparison, electrical regeneration, such as electrodialysis (ED), may solve the problems above. No phase change is involved in this process. In addition, low electrical energy is required and photovoltaic power is capable of proving the necessary energy. In this paper, the performance of Liquid Desiccant regeneration by photovoltaic electrodialysis (PV-ED) was experimentally investigated by considering two important factors, including the initial Desiccant concentration and current intensity. The results showed that the initial Desiccant concentration and current intensity had big impact on the performance of the system. Lower Desiccant concentration and higher current intensity contributed to the current efficiency and solute transport, respectively. In addition, the energy consumption per unit solute migration increased with the increase of both current intensity and Desiccant concentration. The results also indicated that the PV-ED regenerator performed better when the initial Desiccant concentration was low and current intensity was high.
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experimental comparative research on electrodialysis regeneration for Liquid Desiccant with different concentrations in Liquid Desiccant air conditioning system
Energy and Buildings, 2017Co-Authors: Qing Cheng, Xiaosong Zhang, Shun JiaoAbstract:Abstract The issue of energy and environment is increasingly prominent, and air-conditioning system costs a lot of energy in the building. The Liquid Desiccant air-conditioning system is a novel air-conditioner with good energy saving potential, whose energy consumption mainly relies on the regeneration process of Liquid Desiccant. In this paper, an experimental system of electrodialysis (ED) regenerator was set up to confirm the stability of the ED regenerator for the regeneration of Liquid Desiccant with different concentrations and the regeneration performance of the ED regenerator for Liquid Desiccant with different concentrations was investigated. Moreover, the ideal COP of the Liquid Desiccant air-conditioning system and vapor pressure of the acquired strong Desiccant at the exit of the ED regenerator were also evaluated to compare the characteristic of the ED regenerator for Liquid Desiccant with different concentrations. The result shows that besides high concentration, the low temperature is also very important for Liquid Desiccant to have high dehumidification capacity. Moreover, the excessive increase of current will be more harmful to the dehumidification capacity of the acquired strong Liquid Desiccant when Liquid Desiccant concentration is around 35%. Furthermore, when Liquid Desiccant concentration is around 35%, the ED regenerator needs more power to achieve Liquid Desiccant with the same dehumidification capacity.
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recent advancements in Liquid Desiccant dehumidification technology
Renewable & Sustainable Energy Reviews, 2014Co-Authors: Junfei Qian, Xiaosong ZhangAbstract:Liquid Desiccant dehumidification technology is becoming increasingly attractive due to its high efficient utilization of low-grade heat and its effectiveness in dehumidification. Using this technology, energy-efficient air conditioning systems have been developed, which demonstrated superiority over the traditional vapor compression type system by allowing both temperature and humidity to be controlled independently. This paper presented a state-of-the-art review of the research and development in this field, covering the topics of heat and mass transfer models, performance evaluation of Liquid Desiccant dehumidification and regeneration, and technology development of dehumidifiers and regenerators as the most important components of Liquid Desiccant systems. Meanwhile, many detailed systems using solar energy in Desiccant cooling was reported, and some new applications of Liquid Desiccant dehumidification were also introduced.
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Recent advancements in Liquid Desiccant dehumidification technology
Renewable and Sustainable Energy Reviews, 2014Co-Authors: Yonggao Yin, Junfei Qian, Xiaosong ZhangAbstract:Liquid Desiccant dehumidification technology is becoming increasingly attractive due to its high efficient utilization of low-grade heat and its effectiveness in dehumidification. Using this technology, energy-efficient air conditioning systems have been developed, which demonstrated superiority over the traditional vapor compression type system by allowing both temperature and humidity to be controlled independently. This paper presented a state-of-the-Art review of the research and development in this field, covering the topics of heat and mass transfer models, performance evaluation of Liquid Desiccant dehumidification and regeneration, and technology development of dehumidifiers and regenerators as the most important components of Liquid Desiccant systems. Meanwhile, many detailed systems using solar energy in Desiccant cooling was reported, and some new applications of Liquid Desiccant dehumidification were also introduced. © 2013 Elsevier Ltd.
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Performance of solar Liquid Desiccant regeneration
Huagong Xuebao CIESC Journal, 2014Co-Authors: Junfei Qian, Yonggao Yin, Longfei Gao, Xiaosong Zhang, Youchao ZhangAbstract:©, 2014, Chemical Industry Press. All right reserved. To investigate the performance of solar Liquid Desiccant regeneration, experiments in the system of the solar Liquid Desiccant regeneration using LiCl solution as the Liquid Desiccant were performed. The effects of the important operating parameters on the performance of the system were analyzed experimentally. The results showed that, the air and solution mass flow rate had a big positive impact on the performance of the system. The regenerated rate and the energy utilization rate of the system were increased with the Liquid Desiccant regeneration temperature, but the heat collecting efficiency was decreased with the Liquid Desiccant regeneration temperature. The regenerated rate, the heat collecting efficiency and the energy utilization rate of the system would be reduced if the solution concentration increased. And the heat collecting efficiency increased when the solar radiation increased, the system energy utilization rate reduced on the other hand. In addition, the experimental results provided reliable data for the further analysis about how to make use of solar energy efficiently on solution regeneration process.
Saffa Riffat - One of the best experts on this subject based on the ideXlab platform.
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Recent progress in Liquid Desiccant dehumidification and air-conditioning: A review
Energy and Built Environment, 2019Co-Authors: Xiangjie Chen, Saffa Riffat, Xiaofeng Zheng, David ReayAbstract:Abstract This paper presents a literature review on the recent research progress in Liquid Desiccant dehumidification and air conditioning systems. The physical features of various Liquid Desiccant materials and their dehumidification performances have been summarized. With the aim to improve the dehumidification characteristics, mixed solvents Desiccants have become research hot topics recently. Various types of dehumidifiers and their integration with Liquid Desiccant dehumidification system have been reviewed. The combination of Liquid Desiccant dehumidification system with solar collector, vapour compression system, heat pump system, CHP system, etc. have been grouped and compared. It is shown that the majority of the recent research work for Liquid Desiccant dehumidification systems has concentrated on numerical simulations, a considerable amount of works are still required for the practical investigations of innovative material (mixed solvents) and hybrid systems.
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recent developments in solar assisted Liquid Desiccant evaporative cooling technology a review
Energy and Buildings, 2015Co-Authors: Mahmut Sami Buker, Saffa RiffatAbstract:Abstract Cooling by solar energy is one of the key solutions to the global energy and environmental degradation issues. Solar Liquid Desiccant based on evaporative cooling is proposed as an eco-friendly alternative to the conventional vapour compression systems due to its huge untapped energy savings potential. In this paper, the recent works on solar assisted Liquid Desiccant cooling and its various applications combined with evaporative air-conditioning under different climates are reviewed and advantages the system may offer in terms of energy savings are underscored. A basic description of the principles of hybrid solar Liquid Desiccant with direct and indirect evaporative cooling is provided. Finally, solar regeneration methods and recent developments for the Liquid Desiccant air-conditioning system are presented.
Mahmut Sami Buker - One of the best experts on this subject based on the ideXlab platform.
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recent developments in solar assisted Liquid Desiccant evaporative cooling technology a review
Energy and Buildings, 2015Co-Authors: Mahmut Sami Buker, Saffa RiffatAbstract:Abstract Cooling by solar energy is one of the key solutions to the global energy and environmental degradation issues. Solar Liquid Desiccant based on evaporative cooling is proposed as an eco-friendly alternative to the conventional vapour compression systems due to its huge untapped energy savings potential. In this paper, the recent works on solar assisted Liquid Desiccant cooling and its various applications combined with evaporative air-conditioning under different climates are reviewed and advantages the system may offer in terms of energy savings are underscored. A basic description of the principles of hybrid solar Liquid Desiccant with direct and indirect evaporative cooling is provided. Finally, solar regeneration methods and recent developments for the Liquid Desiccant air-conditioning system are presented.
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Recent developments in solar assisted Liquid Desiccant evaporative cooling technology—A review
Energy and Buildings, 2015Co-Authors: Mahmut Sami Buker, Saffa B. RiffatAbstract:Cooling by solar energy is one of the key solutions to the global energy and environmental degradation issues. Solar Liquid Desiccant based on evaporative cooling is proposed as an eco-friendly alternative to the conventional vapour compression systems due to its huge untapped energy savings potential. In this paper, the recent works on solar assisted Liquid Desiccant cooling and its various applications combined with evaporative air-conditioning under different climates are reviewed and advantages the system may offer in terms of energy savings are underscored. A basic description of the principles of hybrid solar Liquid Desiccant with direct and indirect evaporative cooling is provided. Finally, solar regeneration methods and recent developments for the Liquid Desiccant air-conditioning system are presented.
Sanjeev Jain - One of the best experts on this subject based on the ideXlab platform.
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Performance characteristics of cross-flow membrane contactors for Liquid Desiccant systems
Applied Energy, 2015Co-Authors: Sanjeev JainAbstract:Membrane based indirect contact Liquid Desiccant dehumidification technology subsides the serious concern of Liquid Desiccant droplet carryover observed in conventional direct contact Liquid Desiccant systems. In the membrane contactor the air and Liquid Desiccant streams flow in alternate channels in cross-flow arrangement, separated by micro-porous semi-permeable hydrophobic membranes. Only water vapor can pass through the membranes but Liquid Desiccant cannot permeate. A two-dimensional steady-state mathematical model for semipermeable membrane based indirect contactors as dehumidifiers for Liquid Desiccant dehumidification applications has been developed. The model can predict the air and Desiccant parameters inside the dehumidifier and the outlet parameters for a given input parameters. Five different membrane contactors have been fabricated and series of experiments have been conducted to validate the mathematical model. Aqueous solution of lithium chloride has been used as Desiccant. The maximum deviations between experimental and predicted values are within ±10% for outlet specific humidity and outlet enthalpy of air, ±15% deviation in dehumidification effectiveness and ±20% deviation in enthalpy effectiveness. The distributions of major parameters viz. temperature, humidity, concentration, etc., within the contactor have been presented. Parametric analysis has been carried out to study the effects of membrane characteristics, contactor design, fluid flow rates, ambient conditions and Desiccant concentration on the performance of the contactors.
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Simulation of potential standalone Liquid Desiccant cooling cycles
Energy, 2015Co-Authors: Sanjeev JainAbstract:LDCS (Liquid Desiccant cooling systems), capable of achieving dehumidification and cooling with low-grade heat input, can be effectively used for treating fresh air in hot and humid regions. These can also be operated using non-concentrating solar collectors. The present study is concerned with the evaluation of various potential Liquid Desiccant cycles for tropical climatic conditions. Six potential standalone Liquid Desiccant cycles are identified and analyzed to select the best configuration for achieving thermal comfort. A computer simulation model is developed in EES (Equation Solver) software platform to evaluate the performance of all the cycles at various operating conditions. Aqueous solution of LiCl (lithium chloride) is used as Desiccant. Mass and energy balance equations of all the components along with their effectiveness and LiCl property correlation equations are solved simultaneously for given ambient conditions. As the Desiccant circuit is a closed loop, no assumptions are made about its concentration and temperature in the algorithm. Supply air conditions, cooling capacity, COP (capacity and coefficient of performance) and CR (circulation rate) per unit cooling capacity and hot water temperature requirement are used as a measure for analyzing the performance of the different cycles. The effect of hot water temperature on the performance of the cycles is evaluated at ARI conditions. The performances of the cycles are also evaluated for cities selected from each of the climatic zone of India that represent typical tropical climates. Although all the cycles are feasible at ARI and hot and dry conditions, only two cycles can achieve the selected indoor conditions in the peak humid conditions. The results would be useful for selecting suitable Liquid Desiccant cycle for a given climate.
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experimental performance of a Liquid Desiccant dehumidification system under tropical climates
Energy Conversion and Management, 2011Co-Authors: Sanjeev Jain, Sagun TripathiAbstract:Abstract The current energy crisis, climate change and increased air conditioning demands have generated a need for developing technologies based on renewable energy sources. Foremost amongst the cooling technologies are the sorption technologies working on low grade heat that can be supplied by solar energy. Liquid Desiccant technologies seem to be a promising option as these tend to have higher thermal COPs, lower regeneration temperatures, facilitate simultaneous cooling and ease of storage of concentrated Desiccant that can be used during the nonsunshine hours. But few concerns like carryover of Liquid Desiccant in air require further investigations. The Liquid Desiccant system under study incorporates a double channelled exchanger for air to Liquid Desiccant heat and mass transfer. It provides a large surface area for air/Desiccant contact and reduces the carryover as direct contact between Desiccant and air is minimized unlike spray towers, packed bed and falling film designs. Desiccant is heated in a plate heat exchanger using hot water and then regenerated in a regenerator. The set-up comprises of a dehumidifier, along with a regenerator, a cooling tower, plate heat exchangers and a control unit. Experiments were conducted on the system using calcium chloride and lithium chloride as Desiccants by varying parameters like inlet air conditions, hot water temperature and Desiccant concentration in order to evaluate the performance of the system under different operating conditions. The performance of the system is presented in terms of moisture removal rates, dehumidifier and regenerator effectiveness.
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Multi absorber stand alone Liquid Desiccant air-conditioning systems for higher performance
Solar Energy, 2009Co-Authors: Ritunesh Kumar, Sanjeev Jain, P. Dhar, A. K. AsatiAbstract:Abstract Achieving comfortable environment with the use of renewable energy or waste heat without creating the hazardous effects over the earth atmosphere are major challenges in the field of air-conditioning. Liquid Desiccant technology is a promising option. For the past few decades research is going on worldwide to commercialize such systems. Hybrid Liquid Desiccant systems (combination of vapor compression (V-C) and Liquid Desiccant system) have got more attention probably due to higher COPs and lower regeneration temperature for such systems. In the present communication the steady-state performance of stand alone Liquid Desiccant systems has been simulated and analyzed. Falling film designs of absorber and regenerator have been selected for the study due to their lower pressure drops. The simulation of these components has been carried out by solving the basic mass and energy balance equations. These are nonlinear coupled first order differential equations, which have been solved by using fourth order finite difference Runge–Kutta method. The overall system has been simulated using Warner’s technique. Two new stand alone Liquid Desiccant cycles utilizing the potential of Desiccant fully through multiple absorbers have been proposed. The proposed new cycles improve the COP of stand alone systems significantly. A parametric study has also been carried out on these Liquid Desiccant cycles to identify the key design parameters affecting the performance of the system.
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performance analysis of Liquid Desiccant dehumidification systems
International Journal of Refrigeration-revue Internationale Du Froid, 2007Co-Authors: Sanjeev Jain, Pradeep BansalAbstract:Desiccant systems find applications in a very large variety of industrial and daily usage products including the new HVAC installations. An overview of Liquid Desiccant technology has been presented in this paper along with a compilation of experimental performance data of Liquid Desiccant dehumidifiers, empirical dehumidification effectiveness and mass transfer correlations in a useful and easy to read tabular format. The latest trends in this area suggest that hybrid systems are of current interest to HVAC industry, not only for high latent load applications but also for improving indoor air quality. The paper presents a comprehensive comparative parametric analysis of packed bed dehumidifiers for three commonly used Desiccant materials viz. triethylene glycol, lithium chloride and calcium chloride, using empirical correlations for dehumidification effectiveness from the literature. The analysis reveals significant variations and anomalies in trends between the predictions by various correlations for the same operating conditions, and highlights the need for benchmarking the performance of Desiccant dehumidifiers.
Saffa B. Riffat - One of the best experts on this subject based on the ideXlab platform.
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Recent developments in solar assisted Liquid Desiccant evaporative cooling technology—A review
Energy and Buildings, 2015Co-Authors: Mahmut Sami Buker, Saffa B. RiffatAbstract:Cooling by solar energy is one of the key solutions to the global energy and environmental degradation issues. Solar Liquid Desiccant based on evaporative cooling is proposed as an eco-friendly alternative to the conventional vapour compression systems due to its huge untapped energy savings potential. In this paper, the recent works on solar assisted Liquid Desiccant cooling and its various applications combined with evaporative air-conditioning under different climates are reviewed and advantages the system may offer in terms of energy savings are underscored. A basic description of the principles of hybrid solar Liquid Desiccant with direct and indirect evaporative cooling is provided. Finally, solar regeneration methods and recent developments for the Liquid Desiccant air-conditioning system are presented.