Regarding the heat dissipation issue of air-cooled compressors
Thread Content
Dear experts, the poster has a design task that involves pressurizing atmospheric oxygen to 150 atmospheres, with a nominal flow rate of 10 L/min. This is to be achieved through 4 stages of compression, with each stage having a pressure ratio of 3.5; it thus involves a miniature, high-pressure compressor that uses double-acting, stepped-cylinder design. The original poster’s previous work has mainly focused on mechanical design, so they have little knowledge of heat transfer. I recently went through \"Heat Transfer\" edited by Yang Shiming and Tao Wenquan, and I still have many questions. I would like to ask everyone: when the intake air temperature is 25°C and the theoretical exhaust temperature is 146°C, can the exhaust temperature be kept between 30°C and 35°C by using only the radiators outside the cylinders for forced air cooling? If not, to what level can the exhaust temperature be reduced by relying on forced air cooling? What other measures can be used to achieve cooling?
The poster can try using circulating water to cool the tank.
The cylinders of the piston compressors in our factory are all water-cooled! The effect is more stable
How could LZ have such an idea, or get stuck in a dead end! :Lol, I’ve never been involved in design work, but based on years of experience, it’s clear that relying solely on cylinder cooling is far from enough to reduce the temperature from 146 degrees to 35 degrees. A common design approach is to install coolers at the outlets of each stage of the compressor; theoretically, it’s possible to achieve any desired temperature. Of course, a water-cooling jacket for the cylinders is still necessary.
Thank you for the advice. The design requirement is portability, so air cooling would be the best option.
Thanks for the advice. The flow rate required for my design task is very low, at only 10 L/min, so I plan to use forced air cooling directly.
Humbly accept the criticism from the forum moderator. I am considering forced air cooling because the compressor’s flow rate is very low, at 10 L/min, resulting in a low heat generation. Moreover, all the small air compressors available on the market are air-cooled. It’s just that their total pressure ratio is not high. And my requirements are high; it’s 150.
At level 4 and high pressure, the overall volume of the compressor is likely to be fairly large; therefore, the cooler can be placed below the compressor housing, similar to how in common low-pressure micro air compressors, the compressor is located above the air storage tank. If that’s not possible, change the level 4 to level 5 and reduce the compression ratio; this way, the exhaust temperature won’t be so high, and it may become feasible to use air cooling. Furthermore, one cannot consider only the final outlet temperature; what are the exhaust temperatures at the earlier stages? If the same problem persists, the inter-stage cooling issue also needs to be resolved.
Thank you for the advice. An oxygen flow rate of 10 L/min refers to the air intake flow rate of the first-stage cylinder, that is, the oxygen flow rate that needs to be pressurized. Taking factors such as leakage into account, the working volume of the cylinders at stage 4 turns out to be very small, at 0.9140 L, 0.2672 L, 0.08 L, and 0.0232 L respectively; therefore, it is estimated that the overall volume of the compressor will not be large. I hope the imperfection in inter-stage cooling is as close to 0 as possible; in other words, I want the inlet temperature of each stage to be reduced to approximately the initial inlet temperature (25°C). It seems the cooling scheme may need to be redesigned. It’s really like there’s a huge gap between different fields; I’ll go down and think about it carefully.