Renewable Energy Resources and Technologies
Ali Moazemi Goudarzi; Shahab Alizadeh; Hesam Ramezanzadeh
Abstract
In this paper, the absorbent carryover effect in a designed counter-flow enthalpy exchanger is investigated. In a built prototype of the liquid desiccant dehumidifier, air and the absorbent solution are in contact and flow through a packed multi-channel polymer tower in a counter-flow pattern. To avoid ...
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In this paper, the absorbent carryover effect in a designed counter-flow enthalpy exchanger is investigated. In a built prototype of the liquid desiccant dehumidifier, air and the absorbent solution are in contact and flow through a packed multi-channel polymer tower in a counter-flow pattern. To avoid the absorbent carryover, the tower is equipped with an eliminator. Experimental measurements show that applying wick of hydrophilic type material to the channels' surfaces of the eliminator and the enthalpy exchanger, while increasing the rate of dehumidification, reduces the solution carryover effect, however, it does not eliminate it. To eliminate the effect, pumping the solution into the tower is interrupted periodically. It was found that by adjusting the pump switching frequency, the carryover effect can be eliminated. The best result is achieved when the period of switching on state is about a quarter of the off state one and the total period is about 25 seconds. Since the solution pump is turned off frequently, the cost of electrical power is reduced significantly. Also, the measurements show that while the dehumidification ability of the tower is improved in a steady state operation its regeneration performance is not.
Shahab Alizadeh; Hamid Reza Haghgou
Abstract
In a 10-ton capacity pilot plant solar liquid desiccant air conditioner (LDAC) developed, dehumidification of the outside air is achieved through a honeycomb packed-bed heat and mass exchanger, using lithium chloride solution as the desiccant. The dry air obtained from the dehumidification process is ...
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In a 10-ton capacity pilot plant solar liquid desiccant air conditioner (LDAC) developed, dehumidification of the outside air is achieved through a honeycomb packed-bed heat and mass exchanger, using lithium chloride solution as the desiccant. The dry air obtained from the dehumidification process is evaporative cooled inside a cooling pad and directed into the conditioned space. The dilute solution thus produced is concentrated in a honeycomb packed-bed scavenger air regenerator using hot water from flat plate solar collectors. Carryover of the desiccant particles has been avoided by using eliminators. The air conditioner was installed on a 250 m2 area of the fluid mechanics laboratory of Babol University of Technology, a hot and humid location in the north on the Caspian Sea. The experimental data obtained were compared with the predicted results of a model developed for the air conditioner based on HYSIS and CARRIER energy soft-wares. The comparison reveals that good agreement exists between the experiments and the model predictions. The above tests further reveal that the unit has a satisfactory performance in independently controlling the air temperature and humidity of the conditioned space. The inaccuracies are well within the measuring errors of the temperature, humidity and the air and solution flow rates. An efficient heat recovery within the air conditioner resulted in a thermal COP of about 1.5 and an electrical COP of 7. A commercialization study reveals that the operating cost of an LDAC is significantly lower than its conventional counterpart. The costs would further reduce if a storage system was used to store the concentrated solution of liquid desiccant. A simple payback of five years was determined for the solar components of the liquid desiccant system in this study.
