THEORITICAL STUDY FOR COMPACT LIQUID DESICCANT DEHUMIDIFIER / REGENERATOR SYSTEM
Air may be dehumidified when it is brought into contact with a suitable liquid desiccant. Different types of liquid desiccants are available in the market and the application of the proper desiccant in hot humid climates would improve the dehumidification effectiveness. The driving potential for a dehumidification process is the difference in the pressure of the water vapor in the air and the water vapor saturation pressure corresponding to the airdesiccant solution interfacial temperature and concentration of water above the desiccant. The vapor pressure of a liquid desiccant is a function of its temperature and concentration. Among the various desiccants available, lithium chloride, lithium bromide, calcium chloride, and triethylene glycol have received much attention. The present study aims to evaluate numerically the performance of the proposed liquid desiccant dehumidifier system that utilizes calcium chloride solution as a liquid desiccant. The performance parameters for the air dehumidifier were the reduction ratio of the air humidity ratio and the dehumidifier effectiveness. Several benchmarks were carried out under the following operating conditions: The cooling water temperature (10 o C-18 o C), desiccant solution temperature (26 o C-33 o C), air flow rate (3.4-6 l/s), air inlet temperature (38 o C-51 o C), air inlet humidity ratio (21-25 gw/kgda), desiccant solution mass flow rate (0.04-0.13 kg/s), desiccant solution to air mass flow rate ratio (10-26), heating water temperature (42 o C-51 o C), and desiccant solution concentration (20% -45%). The results show that the humidity ratio at the exit from the dehumidifier decreases with increasing the desiccant solution concentration and with decreasing of the desiccant solution temperature. The desiccant solution moisture content decreases with increasing of the desiccant solution temperature and mass flow rate, but it decreases with decreasing of the air inlet humidity ratio. Also, the air temperature leaving the dehumidifier decreases with increasing the desiccant solution concentration and the air inlet humidity ratio, but it decreases with decreasing of the desiccant solution temperature. The desiccant solution temperature decreases with increasing the desiccant solution concentration and with decreasing both of the desiccant mass flow rate and the cooling water temperature, but it is not affected with the air inlet humidity ratio. The desiccant solution moisture content gain increases with increasing each of the desiccant solution concentration, the air inlet humidity THEORITICAL STUDY FOR COMPACT LIQUID DESICCANT DEHUMIDIFIER/REGENERATOR SYSTEM Vol. 3, No. 11, Dec. 2008 353 ratio and the air mass flow rate. It also increases with decreasing desiccant solution mass flow rate and temperature. Also the results show that both of the dehumidifier reduction ratio of the air humidity ratio and the effectiveness increase with the increase of the heating water temperature, the desiccant solution mass flow rate, the desiccant solution to air mass flow rate ratio and the desiccant concentration. Both the reduction ratio of the air humidity ratio and the effectiveness of the dehumidifier decrease with the increase of the cooling water temperature, the desiccant solution temperature and of the air flow rate. The performance parameters were almost unaffected with the inlet air temperature. The dehumidifier reduction ratio of the air humidity ratio slightly increases with the increase of the inlet air humidity ratio, but the dehumidifier effectiveness is almost unchanged with the increase of the inlet air humidity ratio.
Performance Review of Aqueous Calcium Chloride Liquid Desiccant Based Air Dehumidifier for HVAC Applications: A Review
The exponentially increasing need of human comfort in area of conditioned air has given giant thrust in energy consumption, specifically electrical energy, to run air conditioning equipments used in home or industry. Energy demand depletes the fossil fuel reservoir, affects the climate changes adversely and hence it is a matter of utmost concern to save the both. It is becoming almost inevitable to use air conditioning/cooling equipments in summer season in tropical region of the world. Calcium Chloride (CaCl2) is one of the most economical liquid desiccants and used in many ways to reduce the latent heat content of air. In this paper, a review of calcium chloride based air dehumidifier done with insight in basic cycles of working, properties as a liquid desiccant and methods of use in practice for HVAC applications. In addition, the performance review of the calcium chloride based air dehumidifier for HVAC applications since its inception to the recent research going on it concisely given with key effects in its performance parameters to help understand the progress and trends of use. It is evident from the given performance review that calcium chloride based air dehumidifier has progressed well from its simple form of working and experimented in different conditions with and without internal cooling of air dehumidifier in the field of air conditioning. However, there is scope of improvement to satisfy the unmated demand of performance and to accommodate into its fully developed form to take its place in day to day need of air conditioning in place of conventional vapor compression system. KeywordsHeating Ventilation and Air Conditioning (HVAC), Liquid Desiccant Based Air Dehumidifier (LDAD), Hybrid Desiccant Based Air Conditioning (HDBAC), Calcium Chloride (CaCl2), Energy, Latent Heat, Sensible Heat.
The Origins of Jewish Guilt: Psychological, Theological, and Cultural Perspectives
The idea that guilt and Judaism are closely interlinked has a long historical legacy. After discussing recent work on anthropology and emotion focusing on shame and guilt, we examine three theories purporting to account for this link: psychoanalytic, theological, and guilt as a cultural stereotype particularly the notion of the Jewish mother.