Solar/Gas Brayton/Rankine Cycle Heat Pump Assessment

摘要

A 10-ton gas-fired heat pump is currently under development at AiResearch under joint DOE and GRI sponsorship. This heat pump features a highly efficient, recuperated, subatmospheric Brayton-cycle engine which drives the centrifugal compressor of a reversible vapor compression heat pump. The investigations under this program were concerned initially with the intergration of this machine with a parabolic dish-type solar collector. Computer models were developed to accurately describe the performance of the heat pump packaged in this fashion. The study determined that (1) only a small portion (20 to 50 percent) of the available solar energy could be used because of a fundamental mismatch between the heating and cooling demand and the availability of solar energy, and (2) the simple pay back period, by comparison to the baseline non-solar gas-fired heat pump, was unacceptable (15 to 36 years). The program was modified to include investigations of a solar-assisted gas-fired cogeneration system. In this arrangement the subatmospheric Brayton engine produces electrical power and use is made of the engine waste heat at temperatures up to 400F. Parametric data were generated in terms of engine duty cycle and waste heat utilization fraction. The economic analyses show very attractive return on investment for this system, even for very conservative economic factors.