Vapour Compression and Liquid Desiccant Hybrid System for Air Conditioning

2006 ◽  
Author(s):  
Stefano Bergero ◽  
Anna Chiari ◽  
Enrico Nannei
Keyword(s):  
Air Conditioning ◽  
Power Saving ◽  
Operating Conditions ◽  
Dew Point ◽  
Operating Parameters ◽  
Direct Expansion ◽  
Liquid Desiccant ◽  
Hydrophobic Membrane ◽  
Air Conditioning System ◽  
Vapour Compression

The present study examines the performance of a hybrid air-conditioning system in which a vapour compression inverse cycle is integrated with an air dehumidification system working with hygroscopic solution and hydrophobic membrane. This approach may prove to be a valid alternative to the traditional summertime air-conditioning system, which involves cooling the air to below its dew point and subsequently reheating it. The system examined simultaneously cools and dehumidifies the air in an air-LiCl solution membrane vapour exchanger before it enters the conditioned environment. The LiCl solution is cooled by means of a vapour compression inverse cycle that uses the refrigerant KLEA 407C. The heat rejected by the condenser is used to regenerate the solution. A SIMULINK calculation programme was used to simulate the system in steady-state conditions. The performance of the system was analysed on varying significant operating parameters and was compared with that of a traditional direct-expansion air-conditioning plant. The results of the simulations revealed significant power saving which, in certain operating conditions, was as much as 50%.

scholarly journals Performance optimization of polymeric porous membrane-based liquid desiccant air dehumidifier used in air conditioning system

2019 ◽  
Vol 11 (1) ◽  
pp. 55-71
Author(s):  
Ali Mohammad Jafarpour ◽  
Farivar Fazelpour ◽  
Seyyed Abbas Mousavi
Keyword(s):  
Performance Optimization ◽  
Air Conditioning ◽  
Weather Conditions ◽  
Porous Membrane ◽  
Operating Conditions ◽  
Regeneration System ◽  
Liquid Desiccant ◽  
Air Conditioning System ◽  
Air Stream ◽  
Improved Performance

AbstractIn this study an experimental design was developed to optimize the performance and structure of a membrane-based parallel-plate liquid desiccant dehumidifier used in air conditioning regeneration system which operates under high humidity weather conditions. We conducted a series of polymeric porous membranes with different compositions fabricated that were prepared with various weight percentages of polysulfone (PSU), mixed with N-methyl-2-pyrrolidone (NMP) and dimethyl form amide (DMF) solvents. Furthermore, the designed experiments were performed under various operating conditions, indicating that the dehumidification efficiency declines with increasing flow rate, temperature, and humidity. Consequently, a membrane with optimized porosity and moisture permeability was selected which resulted in eliminating the carryover of solution droplets in the air, largely due to separating the flow condition of liquid desiccant (Li Cl) and air. This specific design is also greatly benefited by removing the water vapor from the air stream. The results of mathematical model simulations indicate that the DMF solvent had higher dehumidification capability compared with that of NMP under the optimized operating conditions. Additionally, it can clarify the porosity of the membrane which plays a significant role in the overall performance. Therefore, the fabricated membrane produces fresh cool air, and it can be applied as a guiding sample for designing the membrane-based dehumidifier with improved performance.

Evaluation of membrane-based air pre-dehumidification for a capillary radiant air conditioning system

2020 ◽  
pp. 1420326X2096738
Author(s):  
Zan-She Wang ◽  
Fang-Ting Yin ◽  
Ran Li ◽  
Zhao-Lin Gu
Keyword(s):  
Moisture Content ◽  
Air Conditioning ◽  
Dew Point ◽  
Liquid Desiccant ◽  
Air Conditioning System ◽  
Point Temperature ◽  
Dew Point Temperature ◽  
Temperature Range ◽  
Libr Solution ◽  
The Ideal

The polyvinylidene fluoride hollow fibre membrane air dehumidification tests were carried out between the liquid desiccant solutions and the wet air. Three liquid desiccant solutions of LiBr solution (50%), LiCl solution (35%) and CaCl2 solution (40%) were tested under different wet air conditions. The results showed that all the membrane dehumidification processes were stable. The air moisture content in the outlet of the membrane was maintained as 6.5 g/kg (da)–8.2 g/kg (da) when the air moisture content in the inlet of the membrane was operated from 17.1 g/kg (da) to 32.4 g/kg (da). The dehumidification amount of LiBr solution (50%) and LiCl solution (35%) was more productive. On this basis, a membrane-based air pre-dehumidification process for the capillary radiant air conditioning system was built. Since the ideal dew point temperature range of the indoor air is below 14–17°C according to the cold supply water, all the air moisture content at the membrane outlet is much lower than that of the ideal dew point temperature range, which means non-condensing occurs in the capillary tube surface. The membrane-based air pre-dehumidification process can easily form an adaptive regulation process of humidity with the capillary radiant air conditioning system under different environmental parameters.

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

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.

Development and Design of Cold Radiation Refrigeration Energy Saving Technology of Comfort Air Conditioning

2014 ◽  
Vol 670-671 ◽  
pp. 968-971
Author(s):  
Mao Ren Li
Keyword(s):  
Heat Transfer ◽  
Energy Saving ◽  
Air Conditioning ◽  
Polymer Composite Material ◽  
Operating Conditions ◽  
Dew Point ◽  
Main Body ◽  
Air Conditioner ◽  
Air Conditioning System ◽  
Technical Requirements

This project is mainly used in the comfort air conditioning system, replacing the conventional indoor air conditioning using fan convection cooling form, directly to the traditional air conditioning evaporator by convection heat transfer to type into the radiation heat transfer form, using modern new polymer composite material as the main body of the evaporator, the refrigerant cycle, in the mature theory of refrigeration the design of conventional air conditioning operating conditions of vapor compression on the overall setting of air conditioning design, exploration and design with the radiation air conditioning system technical requirements, the radiant cooling refrigerant system the data acquisition, development and design of intelligent controller and related problem of air conditioner indoor dew point control, thus the formation of completely based on the prototype structure of energy-saving radiation cooling technology of comfort air conditioning.

Thermal energy analysis on liquid desiccant air conditioning system at different desiccant solution parameters

2019 ◽  
Vol 233 (5) ◽  
pp. 1052-1065
Author(s):  
Y Siva Kumar Reddy ◽  
Karthik Balasubramanian ◽  
VP Chandramohan
Keyword(s):  
Heat Capacity ◽  
Thermal Energy ◽  
Air Conditioning ◽  
Energy Analysis ◽  
Operating Parameters ◽  
Liquid Desiccant ◽  
High Concentration ◽  
Air Conditioning System ◽  
Capacity Ratio ◽  
Solution Parameters

Selection of suitable liquid desiccant operating parameters plays a significant role in the design of energy efficient liquid desiccant air conditioning system. To achieve same dehumidification rate from ambient air, different combinations of solution parameters (heat capacity ratio, concentration, and vapor pressure) could be employed in the system. Considering dehumidifier air inlet condition and dehumidification rates are fixed, an analytical study is carried out on the thermal energy analysis of the system at different solution operating parameters. Operating parameters considered in this study are solution concentrations ( Cs = 0.25, 0.3, 0.35 and 0.40) and heat capacity ratios ([Formula: see text] = 2.5, 3, 4 and 5). Control volume which includes a pair of air and solution channels (half width channels) of full scale liquid-to-air membrane energy exchangers (LAMEE) has been chosen to analyze the energy transfer between air and solution. The results indicate system requires lesser chiller load ( Qchiller) at high concentration and low heat capacity ratio ( Cs = 0.40 and [Formula: see text] = 2.5) which is 0.29 kW to achieve 0.61 kW cooling load. This is 99% lesser than the Qchiller at high concentration and high heat capacity ratio ( Cs = 0.40 and [Formula: see text] = 5) and 30% lesser than the Qchiller at low concentration and low heat capacity ratio ( Cs = 0.25 and [Formula: see text] = 2.5). Solution heat addition rate ( Qadd) per kW cooling capacity ( Qcc) at this solution condition is found as 0.85 kW.

scholarly journals Performance analysis of a novel liquid desiccant-vapor compression hybrid air-conditioning system

Energy ◽  
2016 ◽  
Vol 109 ◽  
pp. 180-189 ◽  
Author(s):  
Li Yinglin ◽  
Zhang Xiaosong ◽  
Tan Laizai ◽  
Zhang Zhongbin ◽  
Wu Wei ◽  
...  
Keyword(s):  
Performance Analysis ◽  
Air Conditioning ◽  
Vapor Compression ◽  
Liquid Desiccant ◽  
Air Conditioning System
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