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In recent years, due to the increased fossil fuel costs and environmental concerns, there has been a renewed interest in absorption cooling (using low-grade heat source) systems for refrigeration and space cooling applications. Although, the stand-alone coefficient of performance (COP) is a concern with such systems, absorption cooling can be a useful add-on that improves the overall efficiency of conventional vapor compression cooling cycle. A local company based in Las Vegas which is involved in the development of advanced HVAC technologies, has developed a natural gas fueled internal combustion (IC) engine driven heat pump. This system recovers the rejected heat from the IC engine during the heating cycle, thus, increasing the heat delivered and improving the system’s overall efficiency. However, during the cooling cycle the rejected heat is dissipated to the ambient air through radiators. The overall efficiency of the system can be improved if the heat rejected during the cooling cycle can be recovered and used for space cooling or refrigeration applications. In this study, a vapor compression refrigeration system coupled with an absorption cooling system is simulated using MATLAB. The vapor compression system is driven by a natural gas fueled IC engine and the waste heat from the engine is used to drive the absorption cooling system. The waste heat is recovered both from gas exhaust and engine cooling systems. The developed simulation model is used to find the transients of both the vapor absorption and compressions systems for varied cooling demands. Important parameters such as coolant temperature and exhaust gas temperature are obtained from experimental data. This paper presents the most efficient load distribution between the vapor compression and absorption cooling systems.

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Due to extreme summers in the Desert Southwest region of the U.S., there are substantial peaks in electricity demand. Through a grant from the U.S. Department of Energy, a consortium has been formed between the University of Nevada Las Vegas, Pulte Homes, and NV Energy (formerly known as Nevada Power) to address this issue. The team has been developing a series of approximately 200 homes in Las Vegas to study substation level peak electric load reduction strategies. The targeted goal of the project is a peak reduction of more than 65%, between 1:00 PM and 7:00 PM, compared to code standard housing developments. Energy performances of the homes have been monitored and the results were stored for further analysis. A computer model has been developed for one of the homes in the new development using building energy simulation code, ENERGY 10. Influence of different peak reduction strategies on the electricity demand from the home has been analyzed using the developed model. The simulations predict that the annual electrical energy demand from the energy efficient home compared to a code standard home of the same size decreases by 38%. The simulations have also shown that the energy efficient measures reduce the electricity demand from the home during the peak periods. Simulations on the photovoltaic (PV) orientation show that a south oriented PV system is best suited for a home enrolled to flat electricity pricing schedule and a 220°(40° west of due south) orientation is economically optimal for homes enrolled in the time-of-use pricing. The energy efficiency methods in the building coupled with a 220° oriented PV and two degrees thermostat setback for three hours (from 3:00–6:00 PM) can reduce the peak demand by 62% compared to a code standard building of the same size.