The Stirling cooler is a commonly used refrigeration device that operates based on the Stirling cycle principle, achieving refrigeration effects through the reciprocating motion of the driving piston. Its operating principle is relatively simple, yet it finds widespread applications in practical use.
1. Introduction to Stirling cryocooler:
The Stirling cooler is a thermodynamic cycle device consisting of two heat sources with high heat capacity - the hot source and the cold source - and two working pistons. These pistons change the pressure and volume of the gas through intermittent reciprocating motion, thereby achieving the cooling effect.
2. Stirling cycle principle:
The Stirling cycle is an ideal thermodynamic cycle process, consisting of four stages: isothermal expansion, isochoric cooling, isothermal compression, and isochoric heating. The specific operation is as follows:
- Isothermal expansion stage: The heat from the cold source is transferred to the working gas, causing it to expand, and the piston moves from the cold end to the hot end.
- Isochoric cooling stage: The cold source continues to absorb heat, but the gas no longer expands, and the piston remains at its highest point.
- Isothermal compression stage: The heat source transfers heat to the working gas, causing it to compress, and the piston moves from the hot end to the cold end.
- Isochoric heating stage: The heat source continues to transfer heat, but the gas is no longer compressed, and the piston remains at its lowest position.
3. Operating principle:
The operating principle of a Stirling cooler is based on the Stirling cycle, which achieves refrigeration by cycling through changes in temperature and pressure of the working gas. The specific operation process is as follows:
- Cold source heat absorption: During the isothermal expansion stage, the cold source transfers heat to the working gas, causing it to expand, while the piston moves from the cold end to the hot end. In this process, the working gas absorbs heat and transfers it to the hot end.
- Cooling: During the isochoric cooling stage, the cold source continues to absorb heat, but the gas no longer expands, and the piston remains at its highest point. During this process, the temperature of the working gas decreases, dissipating heat to the cold source.
- Heat source heating: During the isothermal compression stage, the heat source transfers heat to the working gas, causing it to compress, while the piston moves from the hot end to the cold end. In this process, the working gas releases heat and carries it to the cold end.
- Heating: During the isochoric heating stage, the heat source continues to transfer heat, but the gas is no longer compressed, and the piston remains at its lowest position. In this process, the temperature of the working gas increases, and the heat source that absorbs heat takes away the heat required for the refrigeration effect.
4. Viewpoints and understandings:
The operating principle of a Stirling cooler is relatively simple. It achieves refrigeration by driving the reciprocating motion of a piston, which cycles through changes in temperature and pressure of the working gas. Compared to traditional refrigeration equipment, Stirling coolers have the following advantages:
- No need for refrigerant: Stirling cryocoolers use working gas as the refrigeration medium, eliminating the need for traditional refrigerants and thus being environmentally friendly.
- High efficiency and energy saving: Due to the use of reciprocating motion drive in Stirling refrigerators, there is no transmission loss, enabling high energy conversion efficiency and refrigeration effect.
- Silent and environmentally friendly: Stirling refrigerators do not have compressors and evaporators like traditional refrigeration equipment, and they produce almost no noise and vibration during operation, making them more environmentally friendly and comfortable.