EXPERIMENTAL STUDY OF HYBRID LIQUID DESICCANT BASED VAPOR COMPRESSION COOLING SYSTEM

In the kingdom of Saudi Arabia, a vast amount of energy is used for air-conditioning and this paper describes a new approach to air conditioning. In the proposed hybrid cooling system, liquid desiccant is used to remove the latent load and the conventional vapor-compression system is used to provide sensible cooling only. In this experimental study, calcium chloride solution is used as the desiccant to dehumidify the air. Gauze-type structured packing towers are used for the dehumidification of air and also for regeneration of the weak desiccant. The designed packed bed dehumidifier and the regenerator are combined with a 5-ton capacity vapor compression system along with the heat recovery units. This paper presents results from a detailed experimental investigation of the heat and mass transfer in a structured packing dehumidifier and regenerator under a variety of operating conditions. In the present study, for the sake of comparison between hybrid and conventional cooling systems, the COP for the cooling system is defined as the heat removed from the space to be cooled divided by energy input for the cooling system. Three different modes of regeneration are considered for the hybrid cooling system and the COP values are compared with conventional vapor compression system. Results show that the ratio of the outlet-to-inlet absolute humidity reaches a steady state value of about 0.6 and the temperature of air decreased from 48 to 38o C in the dehumidifier of the hybrid system. Moreover, it is found that hybrid cooling system provides higher COP compared with conventional system

Solar pond powered liquid desiccant evaporative cooling

Liquid desiccant cooling systems (LDCS) are energy efficient means of providing cooling, especially when powered by low-grade thermal sources. In this paper, the underlying principles of operation of desiccant cooling systems are examined, and the main components (dehumidifier, evaporative cooler and regenerator) of the LDCS are reviewed. The evaporative cooler can take the form of direct, indirect or semi-indirect. Relative to the direct type, the indirect type is generally less effective. Nonetheless, a certain variant of the indirect type - namely dew-point evaporative cooler - is found to be the most effective amongst all. The dehumidifier and the regenerator can be of the same type of equipment: packed tower and falling film are popular choices, especially when fitted with an internal heat exchanger. The energy requirement of the regenerator can be supplied from solar thermal collectors, of which a solar pond is an interesting option especially when a large scale or storage capability is desired

FUEL CONSUMPTION OF A SPARK IGNITION ENGINE BLENDED WITH MTBE

Gasoline engines are widely used in automotive applications and power generation. In these engines, the combustion of converting the fuel energy into mechanical work through combustion takes place rapidly in cycles. An important parameter used as an indicator to the efficiency of engines is the brake specific fuel consumption (bsfc). The equivalence ratio has an appreciable effect on the engine performance. This paper studies experimentally the effects of using an oxygenate namely methyl teriary butyl eyher (MTBE) on bsfc of a typical spark ignition engine. MTBE, which was blended with unleaded fuel in three ratios, was investigated. The engine sfc was measured at a variety of engine operating conditions using an engine dynamometer set-up. This paper presents the comparison of bsfc between the fuel blended with MTBE and the unleaded fuel. The results are presented in terms of equivalence ratio and their effects are discussed in this paper