Performance evaluation of the electrodialysis regenerator for the lithium bromide solution with high concentration in the liquid desiccant air-conditioning system

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.

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Experimental Research on Regeneration Characteristic of ED Regeneration for Lithium Bromide Desiccant Solution with High Concentration: Operating Condition and Electrode Solution

Energies ◽

10.3390/en13184733 ◽

2020 ◽

Vol 13 (18) ◽

pp. 4733

Author(s):

Qing Cheng ◽

Han Wang

Keyword(s):

Flow Rate ◽

Air Conditioning ◽

Lithium Bromide ◽

Solution Concentration ◽

Regeneration System ◽

High Concentration ◽

Air Conditioning System ◽

Initial Concentration ◽

Libr Solution ◽

Short Time

Electrodialysis is regarded as a novel liquid regeneration method, and the regenerated solution can satisfy the dehumidification requirements even in a hot and humid environment. LiBr solution is an important choice for a liquid desiccant air conditioning system due to its great dehumidifying ability, so it is necessary to conduct experimental exploration of the regeneration characteristics of ED regeneration for LiBr solution. In this paper, the effects of solution concentration, circulation flow rate, current and electrode solution on the performance of the electrodialysis regeneration system were studied by constructing an experimental electrodialysis regeneration system. The results show that growing the starting concentration of the LiBr solution adversely affects the regeneration characteristics of the electrodialyzer and of the air conditioning system dehumidified by the solution. Under test conditions, as the initial concentration of LiBr solution increased from 45% to 55%, the performance coefficient (COP) of the system decreased from 2.12 to 1.05. When the dehumidification requirement is met, the initial concentration of the LiBr solution should be reduced. Increasing the circulating flow rate can improve the regeneration performance of the electrodialyzer and the capability of the air conditioning system dehumidified by the solution, but excessively increasing the circulating flow rate will decrease the regeneration performance of the electrodialyzer and the performance of the air conditioning system dehumidified by the solution. Increasing the current can increase the concentration of the LiBr solution in the regeneration cells in a short time, but it will reduce the regeneration performance of the electrodialyzer and the characteristic of the air conditioning system dehumidified by the solution. The current needs to be minimized when meeting regeneration requirements. With the growth in the flow rate of the electrode solution, the regeneration performance of the electrodialyser decreases continuously.

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Performance evaluation and COP calculation of Triple effect vapour Absorption machine working on Solar Thermal energy

International Journal of Current Engineering and Technology ◽

10.14741/ijcet.v8i01.10890 ◽

2018 ◽

Vol 8 (01) ◽

Author(s):

Nasir Ul Rasheed Rather ◽

S. K. Singh ◽

Umair Nazir

Keyword(s):

Performance Evaluation ◽

Heat Source ◽

Lithium Bromide ◽

Solar Thermal Energy ◽

Night Time ◽

Bromide Solution ◽

Lithium Bromide Solution ◽

Single Effect ◽

Solar Field ◽

Change Material

The research paper deals with performance evaluation of a triple effect vapour absorption machine based on lithium bromide solution. The triple effect VAM at the National Institute of Solar Energy also has a provision of storage of heat and cool in PCM (phase change material) where excess heat from the solar field at peak hours is stored and the excess cooling effect generated at part load is stored in different PCM chambers when no radiation is available, especially at night time. The water in this mixture is the absorbent or refrigerant and Lithium Bromide is the absorber. The required heat source temperature is usually above 80°C for single-effect machines and the COP is in the range of 0.6 to 0.7. In triple effect systems, COP of 1.7 has been demonstrated at 2100C.

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