Thermodynamic studies on alternate binary working fluid combinations and configurations for a combined power and cooling cycle

A combined power and cooling cycle was investigated. The cycle is a combination of the Rankine cycle and an absorption refrigeration cycle. A binary mixture of ammonia and water is partially boiled to produce a vapor rich in ammonia. This vapor is further enriched in a rectifier/condenser and after superheating, expanded through a turbine. The vapor exiting the turbine in this cycle is cold enough to extract refrigeration output. By suitable selection of operational parameters for the cycle, the useful output can have a large range of refrigeration to work ratios. This combined cycle is being proposed for applications with lower temperature heat sources, with the primary objective of producing power. Some examples of energy sources include solar, geothermal, or industrial waste heat.; Evaluating the efficiency of this cycle is made difficult by the fact that there are two different outputs, namely power and refrigeration. An efficiency expression has to suitably weight the cooling component in order to be able to compare this cycle with other cycles. Several expressions are proposed for the first law and second law efficiencies for the combined cycle based on existing definitions in the literature. Some of the developed equations have been recommended for use over others, depending on the comparison being made.; This study extended the application of the cycle to working fluids other than ammonia-water mixtures, specifically to organic fluid mixtures. It was found that very low temperatures (well below ambient) are not achievable using organic fluid mixtures, while with an ammonia-water mixture; temperatures that were substantially below ambient were obtained under similar conditions. Thermodynamic efficiencies obtained with hydrocarbon mixtures are lower than those seen with an ammonia-water mixture as the working fluid.; Based on the exergy analysis, the cycle configuration has been modified to improve its second law efficiency. A significant improvement in the resource utilization efficiency of more than 25% was achieved with the best among the improved schemes. Increased efficiencies can also be obtained for the cases where only work output is desired.