G.B. Chen

Experimental study on a double-orifice two-stage pulse tube refrigerator

This paper describes the basic structure of a two-stage pulse tube refrigerator. A novel phase shifter termed a double-orifice is introduced. The machine was driven by a valved compressor and the on-off timing was controlled by a computer and solenoids. The lowest temperature of 3.1 K at the cold end of the second stage was achieved.

Experimental investigation on the onset and damping behavior of the oscillation in a thermoacoustic prime mover

Abstract Experiments have been made on the onset and damping behavior of the oscillation in a thermoacoustic prime mover with nitrogen as the working fluids. In contrast to the traditions indicating that the damping point coincide with the onset one, we find lags between the onset temperature and the damping temperature in the thermoacoustic oscillation. A hysteretic loop, due to the temperature difference, is recognized for the first time. It is confirmed by all results of the nitrogen of 0.4–2.4 MPa. Some interesting phenomena observed in the experiments are also presented.

A thermoacoustically driven pulse tube refrigerator capable of working below 120 K

Abstract Based on the discussion of the matching problems between the prime mover and pulse tube, a self-made standing-wave thermoacoustic prime mover is used to drive a coaxial single-stage pulse tube refrigerator. A lowest refrigeration temperature of 138 K was obtained from the preliminary tests in 1999. Then, some improvements have been made to the heat exchangers and the connection between prime mover and pulse tube. The minimum cooling temperatures of 119.7 and 117.6 K have been obtained from the recent experiments with helium and helium–argon mixture filling of 2.0 MPa as the working fluids, respectively. It is a great progress for the standing-wave machine and provides the possibility of liquefying natural gas of 0.2 MPa.

Influence of buffer on resonance frequency of thermoacoustic engine

Frequency matching is of great importance to a thermoacoustically driven pulse tube refrigeration system. To compute the resonance frequency of thermoacoustic engines, the fluid impedance method is introduced. The calculations of the thermoacoustic engines with different arrangements of buffer have been carried out. The influence of the buffer arrangements and the volume on the resonance frequency as well as the acoustic power of thermoacoustic engines is also discussed.

Experimental study on a thermoacoustic engine with brass screen stack matrix

A thermoacoustic engine is a new type of pressure wave generator. With no moving parts, it is a simple, reliable, and long-term nonmaintenance machine. It has great potential in space application. An experimental thermoacoustic engine has been fabricated recently. A maximum pressure ratio of 1.12 has been obtained using a working fluid of nitrogen and 1.06 with helium, with corresponding frequencies of 25 Hz and 70 Hz, respectively. The influence of operating conditions and structural parameters on the performance of the engine was also tested.

Investigation on Gedeon Streaming in a Traveling Wave Thermoacoustic Engine

Introducing feedback path, traveling wave thermoacoustic engines realize relatively higher efficiency in thermoacoustic conversion. However, the toroidal topology allows acoustically induced streaming, which can seriously degrade performance of traveling wave thermoacoustic engines. With measurements of pressure and temperature distributions as effective approaches, four methods were applied to study the streaming in the thermoacoustic engine. The effects of Gedeon streaming on the temperature profile, the pressure ratio, and the thermoacoustic conversion efficiency of the engine were experimentally investigated. Experiments show that the performance of the engine can be remarkably improved with efficient streaming suppression. When Gedeon streaming is suppressed completely, maximal pressure ratio of 1.302 with nitrogen at 1.57 MPa as working gas and the maximal pressure difference of 0.63 MPa with working pressure at 2.54 MPa were obtained. This research is of importance for further understanding the mec...

Investigation of a near-63 K isothermal in a pulse tube refrigerator with He-N2 mixtures

The refrigeration performance of a pulse tube refrigerator with He-N2 mixtures has been investigated. Utilizing the phase transition heat of nitrogen, a near-63 K isothermal within a certain range of cooling power is obtained. The temperature and pressure characters of the pulse tube refrigerator in the presence of a liquid-solid phase transition have been studied. A novel configuration of the pulse tube refrigerator with a freezing cryogen accumulator is proposed as an example of possible applications.

Experimental study on pulse tube refrigeration with helium and nitrogen mixtures

Abstract An experimental investigation on two-component multi-phase helium and nitrogen mixtures in a single-stage pulse tube refrigerator was carried out. The experimental results show that both coefficient of performance (COP) and cooling power can be improved to some extent at above 70 K when the nitrogen fraction in the mixture is less than 25%. An approximate stable temperature platform at the triple point 63.15 K of nitrogen, which is independent of nitrogen’s fraction, is obtained when the cooling power is below 7 W.

Experimental Investigation of a Pulse Tube Refrigerator Driven by a Thermoacoustic Prime Mover

A breadboard pulse tube refrigerator driven by a standing-wave thermoacoustic prime mover has been set up to study the relationship among stack, regenerator, and working fluids. The stack of the thermoacoustic prime mover is packed with dense-mesh wire screens because of their low cost and ease of construction. The effect of packing factor in the stack on onset temperature, refrigeration temperature, and input power has been explored. An optimum packing factor of 1.15 pieces per millimeter has been found; this is an empirical value that provides a compromise between enhancing the thermoacoustic effect, and decreasing the heat conduction and fluid-friction losses along the stack. The pulse tube cooler driven by the thermoacoustic prime mover is able to obtain refrigeration temperatures as low as 138 K and 196 K with helium and nitrogen, respectively.

Dynamic simulation of one-stage G-M refrigerator and comparison with experiment

In this paper a mathematical model of a one-stage G-M refrigerator has been made to simulate its dynamic performance. A set of governing equations has been solved by a numerical method. Some P-V diagrams under different refrigeration temperatures have been tested. The calculated results show good agreement with experiment, especially in the hot chamber. The greatest deviation in the cold chamber is about 11%.