High-Power Thermoacoustic Stirling Heat Engine Results

Abstract

We are developing a thermoacoustic Stirling heat engine (TASHE) to drive a pulse tube refrigerator (PTR) and electrical linear alternator for instrument cooling and power generation on a Venus lander. The TASHE will produce acoustic (PV) power and deliver it both to the linear alternator to generate electrical power and to the PTR to generate refrigeration power. Thus, this duplex system will consist of a TASHE, a PTR, and a linear alternator, simultaneously producing cooling and electrical power from an input heat source. The system is expected to be highly efficient, and will have no moving parts at high temperature, which will be very reliable. This paper will discuss our Venus Lander Duplex System (VLDS) conceptual design, results of a trade study that included a single-stage refrigerator, the coldbay thermal performance option with a multiple-stage refrigerator, and initial test results of the Sierra Lobo 12 kW input-power TASHE. The TASHE was designed using DeltaEC software to use 12 kW of input power at the hot heat exchanger to produce 4 kW of acoustic power, with a resulting efficiency of 30%. The TASHE hot heat exchanger operates at 950 K and the cold heat exchangers operate at an ambient temperature of 300 K. The system mean pressure is 3.45 MPa and the pressure amplitude at the TASHE outlet is 12% of the mean pressure. The operating frequency is 30 Hz and is controlled by a gas resonator. For the Venus application, the gas resonator will be replaced by a free-piston resonator, which will reduce acoustic loss significantly, as well as being smaller than the gas resonator, making it more feasible for space applications.