Increase heat transfer efficiency
Thread Content
There is a liquid ammonia storage tank on site, which is vacuum-jacketed. A heat exchanger is used above the tank for cooling and pressure reduction. Because the ammonia gas in the tank floats into the heat exchanger to exchange heat with the refrigerant, the heat exchange efficiency is low. Now that the project has been completed and delivered, it is necessary to increase the heat exchange efficiency without changing the main body. Below is a hand drawn diagram. Please share your thoughts, thank you!
Low heat exchange efficiency? Does it mean that higher temperature and higher pressure require additional discharge? Does the liquid ammonia storage tank need to be kept cold? Because the equipment has been fixed (factors such as material/size), so what can be changed is the so-called refrigerant type or temperature to improve heat exchange efficiency.
If ammonia is not discharged, the heat exchange efficiency is low, which means that the energy transfer effect between the refrigerant and ammonia is low. The refrigerant temperature is very low, about -15°C after passing through the expansion valve. The problem now is that the ammonia gas floats up to the heat exchanger by its own movement. In layman's terms, it is: A big ox pulls a small cart. The jar is vacuum-laminated, so there is no need to wrap it for insulation.
If ammonia is not discharged, the heat exchange efficiency is low, which means that the energy transfer effect between the refrigerant and ammonia is low. The refrigerant temperature is very low, about -15°C after passing through the expansion valve. The problem now is that the ammonia gas floats up to the heat exchanger by its own movement. In layman's terms, it is: A big ox pulls a small cart. The jar is vacuum-laminated, so there is no need to wrap it for insulation.
Then according to your statement, the problem is that there is too little ammonia, resulting in low efficiency, so there is nothing you can do about it... Maybe you should open less on the refrigerant side to save energy.
There are about ten tons of liquid ammonia in the ammonia storage tank. The problem is that the ammonia gas floats by its own movement and exchanges heat with the refrigerant.
I don’t quite understand the purpose of heat exchange. Is it to lower the temperature of liquid ammonia or to prevent liquid ammonia from vaporizing? If it is the former, why not use inner coil or jacket cooling? If it is the latter, what is your basis for saying that the heat exchange efficiency is low? The refrigerant outlet temperature is low, which does not necessarily mean low efficiency. It may also be due to a small amount of heat medium, which means that there is less vaporized ammonia in the tank. Of course, there will not be so much ammonia for heat exchange with the refrigerant. The heat exchange rate is naturally low, and the refrigerant outlet temperature is low. Is the tank pressure high?
The biggest problem should be that liquid ammonia will escape, but the amount of escape is very small... Install an external cooler to condense the escaped ammonia... ----------------------------------------- So back to what I said above, if it is just to condense the gas but the amount of gas is very small, then I really have no choice (actually, this has nothing to do with low efficiency, it is just that the amount of escape is too small)
Yes, it means that the cooler has completed its task. If you simply feel that the refrigerant outlet temperature is low, you can reduce the refrigerant and the outlet temperature will increase.
In order to reduce the tank pressure, a pressure of 5 kg must be maintained inside to liquefy the ammonia in the process storage tank. The current problem is that the heat transfer efficiency is too low due to low ammonia escape, resulting in poor cooling ability. I'm also curious why I didn't consider using ice water jacket cooling before, but used this method to cool the system.
The purpose of the condenser is fulfilled, but the pressure in the system often remains high. So I want to see if there is any way to increase the heat exchange efficiency and enhance the cooling effect without changing the main body.