A Novel Experimental Apparatus of a Liquid Desiccant Air-Conditioning System

A novel experimental apparatus of a liquid desiccant air-conditioning system was introduced. The system differed from similar researches in that it could handle the total load of the conditioned space without any refrigeration equipment and it worked in ventilation mode, which could greatly improve the indoor air quality. The schematic diagram of the system was presented and circulating processes of air, water and lithium chloride solution in the system were introduced. The definition of thermal coefficient of performance (TCOP) for the system was introduced and main operating parameters that could affect TCOP were analyzed. The tested TCOP of the system was 0.72～0.98 in summer and 0.30～0.51 in autumn, which showed that liquid discussant air conditioning system was especially suitable for hot and humid conditions.

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Performance analysis of a liquid desiccant system with an adjustable reflux ratio of regeneration solution

Building Services Engineering Research and Technology ◽

10.1177/0143624416669830 ◽

2016 ◽

Vol 38 (1) ◽

pp. 89-103 ◽

Cited By ~ 1

Author(s):

Xiaofeng Niu ◽

Yue Zhang ◽

Xing Li ◽

Yan Tong ◽

Guangli Zhang

Keyword(s):

Air Conditioning ◽

Coefficient Of Performance ◽

Reflux Ratio ◽

Thermal Coefficient ◽

System Configuration ◽

Liquid Desiccant ◽

Average Growth Rate ◽

Air Conditioning System ◽

Average Growth ◽

Water Condensation

In the liquid desiccant system, the amount of the diluted solution sent to the regenerator has a great influence on the system performance. The liquid desiccant system with an adjustable reflux ratio of regeneration solution was proposed in the paper, and the effect of the solution regeneration reflux ratio on the system performance was analysed by simulation. The energy consumption, the electric coefficient of performance and the thermal coefficient of performance under different water condensation rates and varied solution regeneration reflux ratio were obtained. The results show that, the overall performance of the liquid desiccant system can be improved by reducing the solution regeneration reflux ratio; a 1% decrease in the reflux ratio leads to a 0.56–1.02% average growth rate of electric coefficient of performance and a 0.51–0.95% average growth rate of thermal coefficient of performance. Moreover, when the regeneration temperature is high and the water condensation rate of the process air is low, the improvement from decreasing the solution regeneration reflux ratio is more significant. However, the reflux ratio cannot be reduced to an unlimited extent. There is a rational optimum range of the reflux ratio to achieve high thermal coefficient of performance, the optimum range under low dehumidifying load is different from that under high load. Practical application: The performance of a liquid desiccant system can be improved by the proposed system configuration with an adjustable reflux ratio of regeneration solution, such novel system configuration could be applied for the design of air conditioning system, which is beneficial for the energy saving in building. Moreover, the rational optimum ranges of the reflux ratio to achieve high coefficient of performance under different dehumidifying loads are obtained, which could provide guidelines for the design and operation management of the liquid desiccant based building air conditioning system.

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Solid desiccant dehumidification-based air-conditioning system for agricultural storage application: Theory and experiments

Proceedings of the Institution of Mechanical Engineers Part A Journal of Power and Energy ◽

10.1177/0957650919869503 ◽

2019 ◽

Vol 234 (4) ◽

pp. 534-547 ◽

Cited By ~ 5

Author(s):

Muhammad H Mahmood ◽

Muhammad Sultan ◽

Takahiko Miyazaki

Keyword(s):

Air Conditioning ◽

Evaporative Cooling ◽

Ambient Air ◽

Coefficient Of Performance ◽

Postharvest Quality ◽

Thermal Coefficient ◽

Humidity Ratio ◽

Factors Affecting ◽

Experimental Apparatus ◽

Quality Of Products

This study experimentally investigates desiccant dehumidification and indirect evaporative cooling for agricultural products' storage. Thermodynamic advantages of the proposed system are highlighted and compared to vapor compression systems. Significance of proposed system is discussed in relation to agricultural storage application. Factors affecting the postharvest quality of products are discussed, and consequently, the psychrometric zones are established for optimum storage. Hydrophilic polymeric sorbent-based desiccant units are used for the experimental investigation. An open-cycle experimental apparatus is setup by which desiccant dehumidification and regeneration processes are analyzed at various conditions. Thereby, a novel correlation is developed by which desiccant dehumidification process can be simulated precisely. The correlation is successfully validated against the experimental data of various conditions. Desiccant air-conditioning cycle is analyzed for two cases (i.e. case-A: dry-bulb temperature = 31 ℃, humidity-ratio = 6 g/kg-DA; and case-B: dry-bulb temperature = 13 ℃, humidity-ratio = 6 g/kg-DA) to investigate the proposed system's applicability for agricultural storage. The results show that the thermal coefficient of performance is highly influenced by ambient air conditions and decreases with the increase in regeneration temperature. The thermal coefficient of performance for case-A is higher as compared to case-B, and for both cases, it increases with the increase in wet-bulb effectiveness of the evaporative cooling unit.

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Evaluation of Cooling Water Storage for Liquid-Desiccant Air Conditioning System

Volume 8A: Heat Transfer and Thermal Engineering ◽

10.1115/imece2014-39949 ◽

2014 ◽

Author(s):

Danial Salimizad ◽

Chris McNevin ◽

Stephen Harrison

Keyword(s):

Air Conditioning ◽

Electrical Power ◽

Water Storage ◽

Cooling Water ◽

Operating Conditions ◽

Coefficient Of Performance ◽

Liquid Desiccant ◽

Air Conditioning System ◽

Electrical Power Consumption ◽

Evaporative Cooling Tower

Liquid-desiccant (LD) dehumidification technology has been used to extract moisture from humid air while attempting to consume less electricity than traditional air-conditioning methods. An evaporative cooling tower (ECT) was used as a cooling device to reject the latent heat gained by the system to regenerate the desiccant solution. The performance of an ECT was evaluated both experimentally and through TRNSYS simulations to investigate optimal operating conditions. The ECT often operated in humid conditions which resulted in reduced heat rejection rates and ineffective operation. To improve performance, cooling water storage (CWS) was investigated as a way to reduce ECT usage during periods of higher ambient humidity. To undertake this study, the complete LD system, incorporating CWS, was modelled in TRNSYS for a range of typical operating conditions. The results indicated that operation of the CWS system reduced the electrical power consumption and increased the electrical coefficient of performance (COPE) of the liquid desiccant air conditioning unit system by up to 16%. The total cooling rate improved by up to 6%. Smaller gains in COPT and solar fraction were also found in the simulation results.

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Comparison study of air mixing modes in liquid desiccant based all-air air conditioning systems

Building Services Engineering Research and Technology ◽

10.1177/0143624411418183 ◽

2011 ◽

Vol 33 (4) ◽

pp. 423-435 ◽

Cited By ~ 2

Author(s):

Fu Xiao ◽

XiaoFeng Niu

Keyword(s):

Energy Consumption ◽

Air Conditioning ◽

Coefficient Of Performance ◽

Liquid Desiccant ◽

Total Energy Consumption ◽

Air Conditioning System ◽

Operation Conditions ◽

Air System ◽

Air Mixing ◽

Air Conditioning Systems

Liquid desiccant is an energy-saving, environmentally friendly and healthy means of air dehumidification. A liquid desiccant-based all-air air conditioning system is studied by simulation. Two different modes of air mixing between the return air and the fresh air are compared, that is mixing before and mixing after the liquid desiccant dehumidifier, respectively. System performance and total energy consumption of the two modes under different operation conditions are obtained. The results show that mixing air after dehumidification consumes less energy than mixing air before dehumidification. Coefficient of performance (COP) of the all-air system with air mixing after dehumidification is higher. The differences of COP and energy consumption between the two air mixing modes increase when the outdoor air temperature and relative humidity increase. Practical application: Liquid desiccant based all-air system is quite suitable for museums, libraries and computer centres where water is not allowed to enter the space for property safety and strict thermal-hygrometric control is necessary. The results of this paper provide guidelines on the selection of air mixing modes in liquid desiccant-based all-air systems, considering energy consumption and system COP.

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Performance Test on a Solar Powered Two-Stage Solid Wheel Desiccant Air Conditioning System

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.732-733.609 ◽

2013 ◽

Vol 732-733 ◽

pp. 609-614

Author(s):

Tong Hua Zou ◽

Gu Jia ◽

Fa Li Cao ◽

Rong Yu

Keyword(s):

Relative Humidity ◽

Air Conditioning ◽

Performance Test ◽

Cooling System ◽

Coefficient Of Performance ◽

Outlet Temperature ◽

Thermal Coefficient ◽

Two Stage ◽

Air Conditioning System ◽

Solar Powered

In the paper, changes of both outlet temperature and relative humidity of solar powered two-stage wheel desiccant air conditioning system are tested with time under the typical Tianjin summer condition. It is found that supply air temperature of the solar driven desiccant cooling system could steady below 21 degrees Celsius, and the relative humidity of it is more than sixty percent in most of time of the actual operation. When operating, the thermal coefficient of performance of the whole air conditioning unit is about 0.5, and the reliability of two-stage wheel desiccant air conditioning system is verified.

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Experimental Investigation of Desiccant Dehumidification Cooling System for Climatic Conditions of Multan (Pakistan)

Energies ◽

10.3390/en13215530 ◽

2020 ◽

Vol 13 (21) ◽

pp. 5530

Author(s):

Muhammad Aleem ◽

Ghulam Hussain ◽

Muhammad Sultan ◽

Takahiko Miyazaki ◽

Muhammad H. Mahmood ◽

...

Keyword(s):

Experimental Data ◽

Silica Gel ◽

Air Conditioning ◽

Ambient Air ◽

Climatic Conditions ◽

Coefficient Of Performance ◽

Thermal Coefficient ◽

Polymeric Sorbent ◽

Experimental Apparatus ◽

Desiccant Material

In this study, experimental apparatus of desiccant dehumidification was developed at lab-scale, using silica gel as a desiccant material. Experimental data were obtained at various ambient air conditions, while focusing the climatic conditions of Multan (Pakistan). A steady-state analysis approach for the desiccant dehumidification process was used, and thereby the slope of desiccant dehumidification line on psychrometric chart (ϕ*) was determined. It has been found that ϕ* = 0.22 in case of silica gel which is lower than the hydrophilic polymeric sorbent, i.e., ϕ* = 0.31. The study proposed two kinds of systems, i.e., (i) standalone desiccant air-conditioning (DAC) and (ii) Maisotsenko-cycle-assisted desiccant air-conditioning (M-DAC) systems. In addition, two kinds of desiccant material (i.e., silica gel and hydrophilic polymeric sorbent) were investigated from the thermodynamic point of view for both system types, using the experimental data and associated results. The study aimed to determine the optimum air-conditioning (AC) system type, as well as adsorbent material for building AC application. In this regard, perspectives of dehumidification capacity, cooling capacity, and thermal coefficient of performance (COP) are taken into consideration. According to the results, hydrophilic polymeric sorbent gave a higher performance, as compared to silica gel. In case of both systems, the performance was improved with the addition of Maisotsenko cycle evaporative cooling unit. The maximum thermal COP was achieved by using a polymer-based M-DAC system, i.e., 0.47 at 70 °C regeneration temperature.

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Research on Double-Stage and Multi-Stage Capacitive Deionization Absorption Air-Conditioning System

Processes ◽

10.3390/pr9020395 ◽

2021 ◽

Vol 9 (2) ◽

pp. 395

Author(s):

Feng Cheng ◽

Boqing Ding ◽

Xiuwei Li

Keyword(s):

Air Conditioning ◽

Pure Water ◽

Good Choice ◽

Coefficient Of Performance ◽

Capacitive Deionization ◽

Joint Work ◽

Thermal Regeneration ◽

Air Conditioning System ◽

Multi Stage ◽

Stage System

An absorption air-conditioning system is a good choice for green buildings. It has the superiority in the utilization of renewable energy and the refrigerant is environment-friendly. However, the performance of the traditional absorption system has been restricted by the energy waste in the thermal regeneration process. Capacitive deionization (CDI) regeneration is proposed as a potential method to improve system efficiency. In the new method-based air-conditioning system, strong absorbent solutions and pure water are acquired with the joint work of two CDI units. Nevertheless, the practical CDI device is composed of a lot of CDI units, which is quite different from the theoretical model. To reveal the performance of multiple CDI units, the model of the double/multi-stage CDI system has been developed. Analysis has been made to expose the influence of some key parameters. The results show the double-stage system has better performance than the single-stage system under certain conditions. The coefficient of performance (COP) could exceed 4.5, which is higher than the traditional thermal energy-driven system, or even as competitive as the vapor compression system. More stages with proper voltage distribution better the performance. It also provides the optimization method for the multi-stage CDI system.

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