Sumio Yagyu

Design, simulation, and test results of a heat-assisted three-cylinder Stirling heat pump (C-3)

This paper describes recent results in a project at KUBOTA to develop a gas engine-driven Stirling heat pump using both engine shaft power and engine exhaust heat source. The design, simulation and test results of the third prototype three-cylinder machine (C-3) are presented. The three-cylinder machine is modeled as a combination of two Stirling sub-systems, one a power producer and one a heat pump. These have been separately optimized then joined into the three-cylinder heat-assisted heat pump case. Shaft power is augmented by thermal power. Performance is effectively controlled by the phase shifting of the third piston to adjust the absorbing of thermal power. The test results of the C-3 prototype machine are given and are shown to compare well with predictions made in the Sage simulation code.

Performance characteristics of a gas engine driven Stirling heat pump

This paper describes recent results in a project at KUBOTA to develop an efficient CFC-free multifunctional heat supply system. A heat pump in the system is a gas engine driven Stirling heat pump. The heat pump is mainly driven by engine shaft power and is partially assisted by thermal power from the engine exhaust heat. By proportioning two energy sources to match the heat balance of the driving engine, this heat-assisted Stirling heat pump can be supplied with the maximum share of the original energy fueling the engine and can be operated at the most efficient point. The authors have developed a system heat pump composed of 6 cylinders, the doubled E-3 prototype. This prototype uses helium gas as a working gas and is constructed as two sets of three-cylinder machines, each a combination of two Stirling sub-systems (one a power producer and one a heat pump). Design and performance simulations of the prototype are presented in conjunction with the driving engine characteristics. This heat supply system is expected to produce cooling and heating water at high COP. Developing the system will provide a CFC-free thermal utilization system technology that satisfies both wide heat demands and various fuel systems.

An analytical approach to multi-cylinder regenerative machines with application to 3-cylinder heat-aided Stirling heat pump

This paper describes a method for analysis and optimization of multi-cylinder regenerative machines. The authors have devised the method in a project at KUBOTA to develop an improved gas engine-driven heat pump using both shaft power and exhaust heat sources. Based on combinations of included Stirling cycles, this analytical approach allows use of well-established and validated Stirling simulation models to optimize partial systems. The technique further provides a method of integrating such optimal partial-system Stirling cycles into a complex combination system. It is shown that this remains an optimum solution for the three-cylinder fire assisted heat pump case. Results from hardware tests of the main Stirling heat pump cycle (2-cylinders) are given and compared with analytical expectations using the Sage simulation code. This is extended to validate Sage modelling of 3-cylinder machines.

Performance Characteristics of a Heat-Assisted Stirling Heat Pump.

This paper describes performance simulations and test results of a prototype to develop a multi-fuel gas engine driven Stirling heat pump. It is mainly driven by engine shaft power and is partially assisted by thermal power from the engine exhaust heat source. We have developed the D-3 machine, the fourth generation prototype of the heat-assisted Stirling heat pump. This machine uses helium gas as a working gas and is constructed as a combination of two Stirling sub-systems;one a power producer and one a heat pump. Utilizing both shaft power and thermal power, performance is controlled by phase shifting of the hot-side piston to adjust the absorbing of thermal power. This heat pump produced colling and heating water at high COP over 4 on an indicated basis. Developing this machine will provide a CFC-free thermal utilization system technology that satisfies both wide heat demands and various fuel systems.