J.U. Ahamed

AN ANALYSIS OF ENERGY, EXERGY, AND SUSTAINABLE DEVELOPMENT OF A VAPOR COMPRESSION REFRIGERATION SYSTEM USING HYDROCARBON

Hydrocarbons being natural fluid have drawn much attention of the scientists and researchers for the application as a sustainable material for the vapor compression refrigeration system. This paper presents a comparison of the energetic and exergetic performances of a domestic refrigerator using pure butane and isobutane as refrigerants. The thermodynamic performances such as exergy destruction or losses, exergy efficiency, and coefficient of performances (COP) were investigated. These parameters were measured at varied operating conditions. Exergy and energy efficiencies of isobutane were found to be 50% and 175% higher than that of R-134a. The analysis shows that the performances of butane and isobutane as refrigerants are comparable with HFC134a. It has also been found that at higher evaporating temperatures, the exergy losses are minimal. The maximum exergy loss occurred in the compressor and the value was 69% of the whole losses in the system. Highest sustainability index was found for butane compared to that of R134a and R600a, respectively.

Heat Transfer and Pressure Drop Characteristics in Turbulent Flow Through a Tube

An experimental investigation has been carried out for turbulent flow through a tube with perforated strip inserts. Strips were of mild steels with circular holes of different diameters. Flow varies, with ranging Reynolds numbers from 15,000 to 47,000. Air velocity, tube wall temperatures, and pressure drops were measured for a plain and strip-inserted tube. The heat transfer coefficient and friction factor were found to be 2.80 times and 1.8 times, respectively, that of the plain tube. The heat transfer performance was evaluated and found to be 2.3 times that of the plain tube based on constant blower power.

Prospect of hydrocarbon uses based on exergy analysis in the vapor compression refrigeration system

This paper emphasized on the possibilities of researches in the field of exergy analysis in various usable sectors where vapor compression refrigeration systems are used. Exergy losses, exergy efficiency, second law efficiency and irreversibility of the system components as well as of the whole system are measured. In the vapor compression system, R134a, R290 and R600a are considered as refrigerants. Exergy parameters in the compressor, evaporator, condenser and expansion devices are calculated and analyzed. Exergy losses depend on evaporator temperatures, condensing temperature, refrigerants and ambient temperature. Most of the exergy losses occur in the condenser. Expansion device has the lowest losses. Exergy parameters are compared for different operating temperature. It is found that hydrocarbons (R600a) have 50% higher exergy efficiency than R134a. Mixture of hydrocarbons also shows the best performance based on the exergy analysis.