The Experts below are selected from a list of 2142 Experts worldwide ranked by ideXlab platform
Xiaosong Zhang - One of the best experts on this subject based on the ideXlab platform.
-
selection of optimal mixed liquid Desiccants and performance analysis of the liquid Desiccant Cooling System
Applied Thermal Engineering, 2016Co-Authors: Xiao Zhao, Xiuwei Li, Xiaosong ZhangAbstract:Abstract Liquid Desiccant Cooling System is an energy-conservative and environment-friendly air-conditioning System. Its performance is strongly influenced by the thermal properties of liquid Desiccant, especially the surface vapor pressure. Mixed liquid Desiccant may have better dehumidification efficiency, lower material cost and lower energy consumption. But it is difficult to analyze its thermal properties. To improve on this, our paper proposes a method based on the NRTL equation to predict the vapor pressure of mixed liquid Desiccants. Six absorbent solutions (LiBr/LiCl + CaCl 2 /MgCl 2 + water/methanol) have been analyzed, and Systems employing them have also been investigated. The results show that the dehumidification efficiency of mixed liquid Desiccant was higher than that of a single solution. The LiBr–CaCl 2 –water System can obtain higher COP compared with other Systems under the condition of the same dehumidification performance in summer. Moreover, the LiCl–methanol–water may be a potential absorbent for energy saving. The results are meaningful for the selection of suitable liquid Desiccants and engineering design.
-
A kinetic mass transfer model of liquid dehumidification for liquid Desiccant Cooling System
Energy and Buildings, 2013Co-Authors: Xiuwei Li, Xiaosong Zhang, Fang WangAbstract:Abstract Liquid Desiccant Cooling System (LDCS) is an alternative air-conditioning System with promising energy-saving potential. To further explore the potential of LDCS, it is important to reveal the mass transfer mechanism of dehumidification process. The classical mass transfer model does well in theoretical analysis, but failed to explain the dehumidification reverse phenomenon in experiments. Therefore, this paper proposes a mass transfer model based on the kinetic theory for improvement. Through theoretical and experimental research, it proves the new model clearly describes the dehumidification mechanism and did better in predicting the dehumidification reverse phenomenon. This paper also gives a method through which we can get some important parameters of the new model from the mass transfer coefficient of the classical model.
-
double stage photovoltaic thermal ed regeneration for liquid Desiccant Cooling System
Energy and Buildings, 2012Co-Authors: Qing Cheng, Xiaosong ZhangAbstract:Abstract Photovoltaic-electrodialysis (PV-ED) regeneration is a novel method for liquid Desiccant Cooling System (LDCS), which has a higher performance than the conventional thermal regeneration method by using solar photovoltaic components to drive an electrodialysis regeneration process. However, there are many defects in the previous proposed single-stage PV-ED System. In this paper, a new double-stage photovoltaic/thermal ED regeneration System is presented. Analysis of the performances of the single-stage and double-stage regeneration System is made and the influential factors are investigated. It reveals that the double-stage PVT-ED regeneration System is more applicable than the single-stage PV-ED regeneration System for liquid Desiccant Cooling System. Moreover, comparisons between the single-stage System and the double-stage System show that the double-stage System is more energy efficient than the single-stage System under the optimized working conditions.
-
Progress in selecting Desiccant and dehumidifier for liquid Desiccant Cooling System
Energy and Buildings, 2012Co-Authors: Xiuwei Li, Xiaosong Zhang, Shuo QuanAbstract:Abstract Liquid Desiccant Cooling System (LDCS) is an alternative air-conditioning System with good energy-saving potential. Dehumidification performance is the key part of LDCS; while Desiccant variety and dehumidifier influence the dehumidification performance. However, few works have been done about how to select cost-effective liquid Desiccant and good performance dehumidifier. To improve, we proposed a new method for selecting a cost-effective mixed Desiccant group: it combines the non-random two-liquid equation (NRTL equation) with the Desiccant cost to get the mathematical form of the cost-effectiveness. Meanwhile, through the comparison experiments among different dehumidifiers, we have found out some helpful tips for dehumidifier design: it achieves better effect with rougher surface and adsorption absorption complex plan. These progresses increase the dehumidification performance by more than 50% and could make LDCS more competitive in the future market.
-
Double-stage photovoltaic/thermal ED regeneration for liquid Desiccant Cooling System
Energy and Buildings, 2012Co-Authors: Qing Cheng, Xiaosong ZhangAbstract:Abstract Photovoltaic-electrodialysis (PV-ED) regeneration is a novel method for liquid Desiccant Cooling System (LDCS), which has a higher performance than the conventional thermal regeneration method by using solar photovoltaic components to drive an electrodialysis regeneration process. However, there are many defects in the previous proposed single-stage PV-ED System. In this paper, a new double-stage photovoltaic/thermal ED regeneration System is presented. Analysis of the performances of the single-stage and double-stage regeneration System is made and the influential factors are investigated. It reveals that the double-stage PVT-ED regeneration System is more applicable than the single-stage PV-ED regeneration System for liquid Desiccant Cooling System. Moreover, comparisons between the single-stage System and the double-stage System show that the double-stage System is more energy efficient than the single-stage System under the optimized working conditions.
R Z Wang - One of the best experts on this subject based on the ideXlab platform.
-
use of regenerative evaporative Cooling to improve the performance of a novel one rotor two stage solar Desiccant dehumidification unit
Applied Thermal Engineering, 2012Co-Authors: Yanjun Dai, R Z WangAbstract:Abstract Ongoing research and development works suggest that good System configurations have significant potential for improving the performance and reducing the cost and size of rotary Desiccant dehumidification and air conditioning System. In this paper, a novel Desiccant Cooling System using regenerative evaporative Cooling and a one-rotor two-stage Desiccant Cooling System are analyzed and compared under Air-conditioning and Refrigeration Institute (ARI) summer, ARI humid and Shanghai summer conditions. The objective of this paper is to compare the thermodynamic performance of the two Systems and obtain useful data for practical application. It is found that compared with the conventional Desiccant Cooling System, the novel Desiccant Cooling System with regenerative evaporative Cooling can handle air to a much lower temperature while maintaining good thermal performance. Under ARI summer, ARI humid and Shanghai summer conditions, the minimum attainable supply air temperatures are reduced from 13.5 °C to 7.9 °C, from 14.2 °C to 9.2 °C and from 18.0 °C to 13.0 °C respectively. It is suggested that the novel Desiccant Cooling System with regenerative evaporative Cooling is beneficial to breaking the obstacle of limited temperature reduction encountered by conventional Desiccant Cooling System, especially in the case of extreme high humid conditions.
-
experimental investigation on a one rotor two stage Desiccant Cooling heating System driven by solar air collectors
Applied Thermal Engineering, 2011Co-Authors: Yanjun Dai, R Z WangAbstract:Abstract A solar driven one-rotor two-stage Desiccant co[oling/heating System is experimentally investigated. It consists primarily of a 5 kW Desiccant Cooling System and 15 m 2 of solar air collectors. The Desiccant Cooling/heating System uses solar thermal energy to regenerate Desiccant wheel in summer, and to produce hot air for space heating in winter. In summer, the outlet temperature of solar air collectors is about 60–100 °C. For the solar driven one-rotor two-stage Desiccant Cooling System, the moisture removal can reach 8–9 g/kg and supply air condition is about 22 °C and 60% RH. Experimental results indicated that the average thermal COP in Cooling cycle is 0.95 in hot and humid climate conditions. The solar COP of System is about 0.45 when thermal efficiency of collector is 50%. This suggested that the System could convert more than 40% of the received solar radiant intensity to Cooling power in sunny days. In addition, the effect of regeneration temperature on the System performance is studied. It was found that average of temperature difference between ambient and room can reach 13 °C for space heating in winter. Coupled with Desiccant Cooling System, solar air collectors can realize year-round running.
-
performance comparison between a solar driven rotary Desiccant Cooling System and conventional vapor compression System performance study of Desiccant Cooling
Applied Thermal Engineering, 2010Co-Authors: T.s. Ge, F Ziegler, R Z WangAbstract:Abstract Solar driven rotary Desiccant Cooling Systems have been widely recognized as alternatives to conventional vapor compression Systems for their merits of energy-saving and being eco-friendly. In the previous paper, the basic performance features of Desiccant wheel have been discussed. In this paper, a solar driven two-stage rotary Desiccant Cooling System and a vapor compression System are simulated to provide Cooling for one floor in a commercial office building in two cities with different climates: Berlin and Shanghai. The model developed in the previous paper is adopted to predict the performance of the Desiccant wheel. The objectives of this paper are to evaluate and compare the thermodynamic and economic performance of the two Systems and to obtain useful data for practical application. Results show that the Desiccant Cooling System is able to meet the Cooling demand and provide comfortable supply air in both of the two regions. The required regeneration temperatures are 55 °C in Berlin and 85 °C in Shanghai. As compared to the vapor compression System, the Desiccant Cooling System has better supply air quality and consumes less electricity. The results of the economic analysis demonstrate that the dynamic investment payback periods are 4.7 years in Berlin and 7.2 years in Shanghai.
-
experimental investigation on a one rotor two stage rotary Desiccant Cooling System
Energy, 2008Co-Authors: T.s. Ge, R Z Wang, Youyi LiAbstract:A one-rotor two-stage rotary Desiccant Cooling System (OTSDC), in which two-stage dehumidification process is realized by one Desiccant wheel, was investigated experimentally. The System was proposed to reduce the volume of two-stage rotary Desiccant Cooling System (TSDC) with two Desiccant wheels without reduction in System performance by using the novel configuration. An experimental setup was designed and built to evaluate the System performance under various operation conditions. The effects of different wheel thicknesses at various rotation speeds under Air-conditioning and Refrigeration Institute (ARI) summer and humid conditions were investigated. It is observed that there exits an optimal rotation speed where moisture removal of the System D and thermal coefficient of performance COPth are both optimal. Moreover, the unit with wheel thickness of 100mm performs better for its bigger moisture removal D and higher COPth. Generally speaking, the COPth of this unit is around 1.0 when the regeneration temperature is lower than 80°C. Compared to TSDC, the OTSDC not only preserves the merits of low regeneration temperature and high COPth, but also has a reduced size by about half.
Ruzhu Wang - One of the best experts on this subject based on the ideXlab platform.
-
Theoretical analysis and case study on solar driven two-stage rotary Desiccant Cooling System combined with geothermal heat pump
Energy Procedia, 2015Co-Authors: Xian Li, Ruzhu WangAbstract:Abstract In this paper, a solar hybrid Desiccant air conditioning System, which combines the technologies of two-stage Desiccant Cooling System and geothermal heat pump together, has been configured and theoretically analyzed. The hybrid System mainly includes a two-stage Desiccant Cooling System with design Cooling capacity of 80 kW, a geothermal heat pump for fresh air handling with 75 kW in nominal Cooling capacity, a geothermal heat pump for capillary radiation terminal with Cooling capacity of 244 kW, an evacuated tubular solar collector array of 530 m 2 , a hot water storage tank and a Cooling tower. Performance model of the System has been created in TRNSYS simulation studio. The aim of this paper is to evaluate the performance of the solar hybrid air conditioning System, thereby providing useful data for practical application in the demonstration project. Simulation results show that, under typical weather condition, the solar driven Desiccant Cooling unit can achieve an average Cooling capacity of 70 kW, which contributes 31.4% of the Cooling capacity provided by the hybrid System. Corresponding average thermal COP is about0.83 under Shanghai weather conditions.
-
Performance of two-stage rotary Desiccant Cooling System with different regeneration temperatures
Energy, 2015Co-Authors: Y.j. Dai, Ruzhu WangAbstract:Abstract Increasing attention is being given to energy-saving air conditioning technology in recent years. Using natural refrigerant and driven by low grade thermal energy, rotary Desiccant Cooling System has become a sound alternative solution to conventional vapor compression System. Although one-stage ventilation rotary Desiccant Cooling System is still the main stream, TSDC (two-stage rotary Desiccant Cooling) System recently emerges as the latest development, which can be driven by lower regeneration temperature (50–90 °C) compared with one-stage System. In this paper, performance of TSDC with different regeneration temperatures in two stages is analyzed. First integrated mathematical model of TSDC System is established by combing models of different components. Cooling power and COPth (thermal coefficient of performance) are utilized as performance indicators. Then System performance with respect to different combinations of two regeneration temperatures are simulated and discussed, while optimization investigation is also conducted to obtain maximum COPth with same Cooling power. Under the simulation condition, results show that Cooling power of the System increases with the increase of regeneration temperatures, however, COPth decreases. Also, when the first stage operates in higher regeneration temperature, TSDC System can obtain better performance reflecting in both Cooling power and in COPth. Moreover, with the same Cooling power provided, COPth of TSDC System obtains a minimum value when temperatures of the two stages approach.
-
Feasible study of a self-cooled solid Desiccant Cooling System based on Desiccant coated heat exchanger
Applied Thermal Engineering, 2013Co-Authors: Tianshu Ge, Ruzhu Wang, Y. LiAbstract:Abstract Solid Desiccant Cooling technology has become a research focus for its features of energy-saving and eco-friendly. However, widely adopted rotary Desiccant wheel Cooling System can't realize inner-Cooling dehumidification process. In this paper, a novel self-cooled solid Desiccant Cooling System (SCDHE) is developed by integrating Desiccant coated heat exchanger and regenerative evaporative cooler. In the System, regenerative evaporative cooler is adopted to produce chilled water, which is again pumped into Desiccant coated heat exchanger in dehumidification process to realize self-cooled dehumidification process. Similarly, in regeneration process, hot water heated by low grade thermal energy is adopted to regenerate the coated Desiccant material. A mathematical model is established to validate the feasibility and to analyze performance of this novel System. Also, effects of ambient air condition are predicted. It is found that SCDHE System is feasible, it can provide satisfied supply air to conditioned room under simulated ARI summer condition, and the required regeneration temperature is from 50 to 80 °C which is lower than rotary wheel Desiccant Cooling System. Also, there exists an optimal switch time and suitable control mode for System to obtain enhanced performance in terms of Cooling power. Compared with conventional DCHE Cooling System without regenerative evaporative Cooling, SCDHE System can provide satisfied supply air while conventional System cannot, also it can obtain increased Cooling power. Under simulation condition, Cooling power of SCDHE System increases by about 30% compared with conventional DCHE Cooling System.
-
Use of compound Desiccant to develop high performance Desiccant Cooling System
International Journal of Refrigeration-revue Internationale Du Froid, 2007Co-Authors: Ji-tao Wu, Ruzhu WangAbstract:Abstract The paper is aimed to develop a high performance rotary solid Desiccant Cooling System using a novel compound Desiccant wheel (DW). The unique feature of the Desiccant wheel is that it can work well under a lower regeneration temperature and have a higher dehumidification capacity due to the contribution of the new compound Desiccant materials. Experimental results indicate that the novel Desiccant wheel under practical operation can remove more moisture from the process air by about 20–40% over the Desiccant wheel employing regular silica gel. A mathematical model that is used to predict the System performance has been validated with the test results. By integrating the Desiccant wheel with evaporative Cooling, heat recovery and heating for regeneration sections, a solid Desiccant Cooling System can be formed. Simulation results show that because of the use of the new compound Desiccant, the Desiccant Cooling System can work under much lower regeneration temperature and have a relative high COP, thus low grade thermal energy resources, such as solar energy, waste heat, etc., can be efficiently utilized to drive such a Cooling cycle.
K.f. Fong - One of the best experts on this subject based on the ideXlab platform.
-
solar Desiccant Cooling System for hot and humid region a new perspective and investigation
Solar Energy, 2020Co-Authors: K.f. Fong, C K LeeAbstract:Abstract With the urge for zero energy buildings, the increasing use of renewable energy sources like solar power is indispensable. Besides, the better utilization of renewable energy sources is also critical. Solar Cooling has been a hot topic, in particular the solar Desiccant Cooling System for use in hot and humid regions. In response to a recent study, the role of the Desiccant wheel in a solar Cooling System under such climatic conditions was reviewed through year-round dynamic System simulation using TRNSYS. It was found that the use of thermally-driven Desiccant Cooling cycle in combination with absorption Cooling was not a good choice for general application when zone humidity control was not mandatory. Rather, the proposed operation of the Desiccant wheel at a higher speed for energy recovery only without heat regeneration offered 9.5% improvement in the solar fraction and 11.5% reduction in the total primary energy consumption, as compared to the former one when the seasonal effect was also taken into account. The merit of the proposed solar Cooling System with energy recovery increased with the expected improvement in the grid thermal efficiency in long term, which further confirmed the appropriateness of the recommended design strategy.
-
investigation on solar hybrid Desiccant Cooling System for commercial premises with high latent Cooling load in subtropical hong kong
Applied Thermal Engineering, 2011Co-Authors: K.f. Fong, T T Chow, A M L FongAbstract:This study found that the solar hybrid Desiccant Cooling System (SHDCS) was more effective to handle the premises with high latent Cooling load in the hot and humid climate compared to the conventional airconditioning System. The SHDCS was designed to use the solar-thermal Desiccant Cooling to tackle the latent load; and the electrical vapour compression refrigeration to cater the sensible load. In this study, the typical commercial premises with high latent load were the Chinese restaurant and the wet market. The effectiveness of SHDCS included both better indoor Cooling performance and higher year-round energy-saving potential. The annual primary energy consumption of SHDCS could be lower than that of the conventional System by 49.5% in the Chinese restaurant and 13.3% in the wet market. For the premises with more stringent temperature and humidity requirements, like the Chinese restaurant, the contribution of SHDCS in energy saving would be significant. Utilization of solar energy could ensure the energy-saving potential of SHDCS for the premises with high latent load. As a whole, the study assures the wider application of solar air-conditioning in the subtropical Hong Kong.
-
advancement of solar Desiccant Cooling System for building use in subtropical hong kong
Energy and Buildings, 2010Co-Authors: K.f. Fong, T T Chow, L S ChanAbstract:Abstract The solar Desiccant Cooling System (SDCS) had a saving potential of the year-round primary energy consumption as compared to the conventional air-conditioning System for full fresh air application in the subtropical Hong Kong. In order to further enhance its energy efficiency, advancement of the basic SDCS was carried out through a strategy of hybrid design. Six hybrid System alternatives of SDCS were therefore proposed, three for full fresh air design while another three for return air design for the building zone. Year-round performance evaluation of each solar hybrid Desiccant Cooling System was conducted for typical office application under different climatic and loading conditions. All the six hybrid System alternatives were found technically feasible, with up to 35.2% saving of year-round primary energy consumption against the conventional air-conditioning Systems. Among the hybrid alternatives, recommendations were made on the SDCS hybridized with vapour compression refrigeration for full fresh air design; and the SDCS hybridized with vapour absorption refrigeration for return air design, since they had the saving potentials of both primary energy and initial cost. These two hybrid System alternatives used evacuated tubes, a more economical type of solar collectors compared to the PV or PVT panels.
-
Simulation–optimization of solar-assisted Desiccant Cooling System for subtropical Hong Kong
Applied Thermal Engineering, 2010Co-Authors: K.f. Fong, T T Chow, L S ChanAbstract:Abstract Solar Cooling is a novel approach, which primarily makes use of solar energy, instead of electricity, to drive the air-conditioning Systems. In this study, solar-assisted Desiccant Cooling System (SADCS) was designed to handle the Cooling load of typical office in the subtropical Hong Kong, in which half of the building energy is consumed by the air-conditioning Systems. The SADCS mainly consisted of Desiccant wheel, thermal wheel, evaporative coolers, solar air collectors and gas-fired auxiliary heater, it could directly tackle both the space load and ventilation load. Since the supply air flow is same as the outdoor air flow, the SADCS has a feature of sufficient ventilation that enhances the indoor air quality. Although it is inevitable to involve the auxiliary heater for regeneration of Desiccant wheel, it is possible to minimize its usage by the optimal design and control scheme of the SADCS. Through simulation–optimization approach, the SADCS can provide a satisfactory performance in the subtropical Hong Kong.
-
simulation optimization of solar assisted Desiccant Cooling System for subtropical hong kong
Applied Thermal Engineering, 2010Co-Authors: K.f. Fong, T T Chow, L S ChanAbstract:Abstract Solar Cooling is a novel approach, which primarily makes use of solar energy, instead of electricity, to drive the air-conditioning Systems. In this study, solar-assisted Desiccant Cooling System (SADCS) was designed to handle the Cooling load of typical office in the subtropical Hong Kong, in which half of the building energy is consumed by the air-conditioning Systems. The SADCS mainly consisted of Desiccant wheel, thermal wheel, evaporative coolers, solar air collectors and gas-fired auxiliary heater, it could directly tackle both the space load and ventilation load. Since the supply air flow is same as the outdoor air flow, the SADCS has a feature of sufficient ventilation that enhances the indoor air quality. Although it is inevitable to involve the auxiliary heater for regeneration of Desiccant wheel, it is possible to minimize its usage by the optimal design and control scheme of the SADCS. Through simulation–optimization approach, the SADCS can provide a satisfactory performance in the subtropical Hong Kong.
L S Chan - One of the best experts on this subject based on the ideXlab platform.
-
advancement of solar Desiccant Cooling System for building use in subtropical hong kong
Energy and Buildings, 2010Co-Authors: K.f. Fong, T T Chow, L S ChanAbstract:Abstract The solar Desiccant Cooling System (SDCS) had a saving potential of the year-round primary energy consumption as compared to the conventional air-conditioning System for full fresh air application in the subtropical Hong Kong. In order to further enhance its energy efficiency, advancement of the basic SDCS was carried out through a strategy of hybrid design. Six hybrid System alternatives of SDCS were therefore proposed, three for full fresh air design while another three for return air design for the building zone. Year-round performance evaluation of each solar hybrid Desiccant Cooling System was conducted for typical office application under different climatic and loading conditions. All the six hybrid System alternatives were found technically feasible, with up to 35.2% saving of year-round primary energy consumption against the conventional air-conditioning Systems. Among the hybrid alternatives, recommendations were made on the SDCS hybridized with vapour compression refrigeration for full fresh air design; and the SDCS hybridized with vapour absorption refrigeration for return air design, since they had the saving potentials of both primary energy and initial cost. These two hybrid System alternatives used evacuated tubes, a more economical type of solar collectors compared to the PV or PVT panels.
-
Simulation–optimization of solar-assisted Desiccant Cooling System for subtropical Hong Kong
Applied Thermal Engineering, 2010Co-Authors: K.f. Fong, T T Chow, L S ChanAbstract:Abstract Solar Cooling is a novel approach, which primarily makes use of solar energy, instead of electricity, to drive the air-conditioning Systems. In this study, solar-assisted Desiccant Cooling System (SADCS) was designed to handle the Cooling load of typical office in the subtropical Hong Kong, in which half of the building energy is consumed by the air-conditioning Systems. The SADCS mainly consisted of Desiccant wheel, thermal wheel, evaporative coolers, solar air collectors and gas-fired auxiliary heater, it could directly tackle both the space load and ventilation load. Since the supply air flow is same as the outdoor air flow, the SADCS has a feature of sufficient ventilation that enhances the indoor air quality. Although it is inevitable to involve the auxiliary heater for regeneration of Desiccant wheel, it is possible to minimize its usage by the optimal design and control scheme of the SADCS. Through simulation–optimization approach, the SADCS can provide a satisfactory performance in the subtropical Hong Kong.
-
simulation optimization of solar assisted Desiccant Cooling System for subtropical hong kong
Applied Thermal Engineering, 2010Co-Authors: K.f. Fong, T T Chow, L S ChanAbstract:Abstract Solar Cooling is a novel approach, which primarily makes use of solar energy, instead of electricity, to drive the air-conditioning Systems. In this study, solar-assisted Desiccant Cooling System (SADCS) was designed to handle the Cooling load of typical office in the subtropical Hong Kong, in which half of the building energy is consumed by the air-conditioning Systems. The SADCS mainly consisted of Desiccant wheel, thermal wheel, evaporative coolers, solar air collectors and gas-fired auxiliary heater, it could directly tackle both the space load and ventilation load. Since the supply air flow is same as the outdoor air flow, the SADCS has a feature of sufficient ventilation that enhances the indoor air quality. Although it is inevitable to involve the auxiliary heater for regeneration of Desiccant wheel, it is possible to minimize its usage by the optimal design and control scheme of the SADCS. Through simulation–optimization approach, the SADCS can provide a satisfactory performance in the subtropical Hong Kong.