Gas-Fueled Engine-Driven Air Conditioning and Refrigeration Systems for Commercial Buildings

GAS-FUELED ENGINE-DRIVEN AIR CONDITIONING AND REFRIGERATION SYSTEMS FOR COMMERCIAL BUILDINGS Bruce B. Lindsay Project Manager commercial Space conditioning Gas Research Institute 8600 W. Bryn Mawr Avenue Chicago, IL 60631 Since 1985, the author has been involved in a program to develop a nominal 150 ton gas-fueled engine-driven water chiller for commercial buildings. The packaged system has been designed, fabricated, and operated satisfactorily in the laboratory and in a 4 so-bed hospital. The engine chiller has subsequently been redesigned to improve performance, increase capacity, and reduce the footprint, and is undergoing field tests at seven sites to verify performance and reliability. The engine chiller has produced 142 tons of cooling at a COP of 1.4 at ARI full load conditions. The heat from the engine may be recovered to drive an optional absorption chiller package, providing an additional 35 tons of cooling and increasing the system COP to 1. 75. The system is comprised of a modified 454 cubic inch engine, twin screw compressor, and advanced microprocessor controls. The engine chiller, by capitalizing on available vapor compression equipment and low cost automotive engines, can meet a highly competitive cost goal of less than $400/ton. The engine's ability to vary speed greatly improves the perforruance of the compressor at part load. Further, the engine can be operated above design speeds for short periods to provide additional peaking capacity. The engine chiller was experimentally installed at a hospital in Manchester, New Hampshire, to evaluate actual system operations and installation procedures. The chiller system, including the absorption package, exhibited an average COP approaching 2.0. The preliltlinary results of the field experiruent were integrated into a new design that radically simplified the package and improved its perforruance. The new design was tested in a seven unit field test during the summer of 1987. The prototype chillers w~re installed in a variety of comruercial buildings, including hotels, office buildings, apartment buildings, and ltlanufacturing facilities. The units have demonstrated a fleet availability of 96% with over 5000 hours of operation. Market assessruents and economic analyses have demonstrated that a huge potential for gas-fueled engine-driven cooling systems exists, especially in regions of the United States that have high electric demand charges. The superior part-load performance of the engine chiller, coupled with its minimal electric requirements, makes it an ideal peaking unit. Gasfueled cooling systems can significantly reduce peak electric demand growth for utilities and minimize investment in new generating capacity. The development program has been expanded to a range of gas engine-driven cooling systerus from 20-ton DX packages to soo-ton liquid chillers. Additionally, an integrated engine ch~llerjdesiccant deh~rnidification system is being developed wh~ch should greatly ~mprove occupant comfort while reducing energy costs.