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 assessment of a membrane liquid desiccant dehumidification cooling system based on experimental investigations
A membrane-based liquid desiccant dehumidification cooling system is studied in this paper for energy efficient air conditioning with independent temperature and humidity controls. The system mainly consists of a dehumidifier, a regenerator, an evaporative cooler and an air-to-air heat exchanger. Its feasibility in the hot and humid region is assessed with calcium chloride solution, and the influences of operating variables on the dehumidifier, regenerator, evaporative cooler and overall system performances are investigated through experimental work. The experimental results indicate that the inlet air condition greatly affects the dehumidification and regeneration performances. The system regeneration temperature should be controlled appropriately for a high energy efficiency based on the operative solution concentration ratio. It is worth noting that the solution concentration ratio plays a considerable role in the system performance. The higher the solution concentration ratio, the better the dehumidification performance. However simultaneously more thermal input power is required for the solution regeneration, and a crystallization risk in the normal operating temperature range should be noted as well. The system mass balance between the dehumidifier and regenerator is crucial for the system steady operation. Under the investigated steady operating condition, the supply air temperature of 20.4°C and system COP of 0.70 are achieved at a solution concentration ratio of 36%.
Neurology, psychology, and extraordinary religious experiences
Temporal lobe epilepsy and certain personality disorders often result in experiences described as “religious.” TLE research suggests a possible neurological basis for such experiences. Immediately the question arises about the authenticity of these experiences as religious. An experience is authentic if it furthers the authentic growth of the subject, regardless of what triggered it. So pathology may occasion authentic religious experiences, even as history exemplifies. For practical purposes, the further question about God in religious experience is secondary. The exception, miraculous occurrences, should not be granted without sufficient reason. This approach dissolves all conflict between science and faith.