Analysis of a novel combined thermal power and cooling cycle using ammonia-water mixture as a working fluid.

摘要

A combined thermal power and cooling cycle is proposed. Ammonia-water mixture is used as a working fluid. The proposed cycle combines Rankine cycle and absorption refrigeration cycle. It can provide power output as well as refrigeration with power generation as a primary goal. The concept of this cycle is based on the varying temperature boiling of a multi-component working fluid. The boiling temperature of the ammonia-water mixture increases as the boiling process proceeds until all liquid is vaporized, so that a better thermal match is obtained in the boiler. The proposed cycle takes advantage of the low boiling temperature of ammonia vapor so that it can be expanded to a low temperature while it is still in a vapor state or a high quality two phase state. This cycle can be used as a bottoming cycle using waste heat from a topping cycle and can be used as an independent cycle using low temperature sources such as geothermal and solar energy.; Thermodynamic properties of the ammonia-water mixture are of technical importance to predict the performance of the proposed cycle. A new method is developed using Gibbs free energy equations to compute the pure component of ammonia and water properties, using bubble and dew point temperature equations developed from the experimental data in the literature for the mixture phase equilibrium calculations. Results have shown very good agreement with the experimental data and other literature data.; This study has also conducted the first and second law thermodynamic analyses of the proposed cycle. The mass composition of binary working fluid is considered in the second law analysis while most of the studies in the literature treat a binary working fluid as a simple fluid in the second law analysis. A comparison of the proposed cycle and the conventional Rankine cycle under the same thermal boundary conditions shows the advantage of the proposed cycle using ammonia-water mixture as a working fluid.; A completed cycle simulation program is developed and shows the performance of the proposed cycle with different parameters.