Small Recuperated Gas Turbine APU Concept to Abate Concern About Emissions, High Fuel Cost, and Noise

Abstract

During the last decade microturbines in the 30 to 250 kW power range have been in service, but they have not been produced in significant enough quantities to impact the DG market due to a combination of factors including their high cost, modest efficiency, utility institutional concerns, and low interest in CHP use in the USA, although the latter could change as a result of fuel cost escalation. Very small gas turbines (ie. less than 10 kW) have been investigated periodically over the years, mainly for potential military use, but to date have not found a niche. This could well change with over 20 states now having instigated idling regulations that limit or prohibit heavy duty truck diesel engine idling. With emphasis on reducing emissions and noise levels this essentially implies that in the future a small APU will be required to provide the truck’s stationary electrical needs and cabin climate control. While there will be several power source types vying for this potentially large market, a small gas turbine APU is viewed as having attractive features which include low emissions, low acoustic signature, vibration-free operation, compact and light weight package, obviates the need for oil lubrication and liquid coolant systems, ease of cold weather starting, immediate response, and the use of fuel from the truck tank. In this paper a small recuperated gas turbine APU concept rated at 5kW is discussed including component design considerations, layout features, engine performance, and target cost. The conservative design of the APU is based on the use of existing materials and state-of-the-art gas turbine technology, and is amenable to high volume automated manufacturing processes. A competitive cost is projected if the proposed APU of modular construction was fabricated in large quantities like the production of vehicular turbochargers in Europe.