What is the concept of internal pressure ratio?
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This post was last edited by sunjl1981 on 2013-1-6 20:09. During the operation of a screw-type refrigeration compressor, in order to minimize operating power consumption, it is necessary for the internal pressure ratio to be as close as possible to the external pressure ratio, thereby ensuring efficient operation. Does anyone know what the concept of internal pressure ratio is? Is it the ratio of internal volumes? (External pressure ratio = condensation pressure/evaporation pressure) # hcbbs
Screw refrigeration compressors belong to the category of positive-displacement compressors; they feature internal compression and possess a certain internal pressure ratio. The operating range of such compressors is very wide, and their operating pressure ratio (condensing pressure/evaporating pressure), which is also the external pressure ratio, varies depending on the operating conditions. This requires that the internal pressure ratio of the screw refrigeration compressor change accordingly, so that it is close to or equal to the external pressure ratio, thereby minimizing the energy consumption of the machine and ensuring most efficient operation. Otherwise, an isochoric compression or expansion process will occur, resulting in increased energy consumption by the compressor. The greater the difference between the internal pressure and the external pressure, the more work is consumed. Therefore, in order to enable the machine to operate economically over the long term, it is necessary to adjust the internal volume ratio of the machine so that the internal pressure ratio is close to or equal to the external pressure ratio. The formula for calculating the external pressure ratio is: External pressure ratio = Condensation pressure + Exhaust pressure (gauge pressure) + 0.1 / Evaporation pressure + Suction pressure (gauge pressure) + 0.1
Content ratio: the ratio of the volume at the completion of inhalation to the volume at the moment the exhaust port opens. The non-adjustable specific volume ratio is fixed during the manufacturing of the compressor ； The adjustable specific volume ratio can be adjusted during operation.
The last edit to this post was made by 181128425 on 2010-5-5 at 16:12. An explanation of the internal pressure ratio: The compression of gas in a screw-type refrigerator occurs simultaneously within the volume between a pair of teeth on the driving rotor and the driven rotor; this is referred to as a basic volume pair, while each individual tooth volume is called a basic volume. As the rotor rotates, the volume value of the elementary volume (pair) changes periodically. The internal compression of the gas occurs within the angular range where the elementary volume is isolated from the intake and exhaust ports, and the pressure during this period is referred to as the internal pressure. The gas pressure at the moment when the elemental volume (pair) is connected to the exhaust port is called the final pressure, and the ratio of this value to the suction pressure is called the internal pressure ratio.