Seeking advice on heat exchanger type selection
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This post was last edited by Zhenglily on 2018-4-20 at 10:26. Hello Hai, I’ve encountered a problem recently: there are 3 operating conditions in the workshop, and a heat exchanger needs to be used to cool down heat transfer oil at 120 degrees Celsius. Condition 1 requires 5.375 KW of heat exchange capacity, Condition 2 requires 10.75 KW, and Condition 3 requires 18 KW. The heat transfer oil flow rate is 2–3 m3/h. I would like to select a heat exchanger that can meet the above three operating conditions, with a high temperature control accuracy (within plus or minus 1 degree Celsius). I am considering using air cooling; the manufacturer says that under operating condition 3, an air cooling system requires a larger heat exchange area, and it is also greatly affected by the temperature in the workshop. Heat exchange is carried out using 7-degree Celsius chilled water coil exchangers; due to the large temperature difference (the temperature of the heat transfer oil being 120 degrees Celsius), the control accuracy is low. Is there a type of heat exchange that can cover the above three scenarios while offering high control precision?
The issue is rather vague; it is recommended to entrust the task to a heat exchanger manufacturer – they will provide you with on-site solutions when you purchase their equipment.
The load differences are significant, and the temperature difference between the cold and hot sides is also large. Could a floating-head heat exchanger be considered? For temperature control, could a bypass system be used alongside the heat exchanger?
To what temperature needs this heat transfer oil to be reduced? As for using water at a temperature of 7 degrees Celsius (the cost is too high), it is recommended to use radiators with forced air circulation
I edited it again; it should be less blurry now. I asked the manufacturers, who all assured me that there would be no problems (with tubular heat exchangers and air coolers). When I brought this up for discussion with the design institute, they rejected it
Well, at that time it was considered that the temperature difference between 7-degree chilled water and heat transfer oil was too large, making heat exchange difficult to control; moreover, such a large temperature difference reduced the service life of the pipes. The 7-degree heat exchange scheme was rejected. Is a forced-air cooling radiator the same as an air cooler?
I think it’s sufficient to use direct water cooling; the heat transfer oil can be routed partially through a bypass, controlled by valves, with the water flow rate adjusted for maximum load, and temperature control applied afterward. That should work. Be sure to include expansion joints
Your process requirements may have limitations, but air-based ones will work as well. Fins can be added outside the tube columns. It’s still recommended to find a company to show you. Here, your responses are limited, which makes discussion difficult. Your data throughput is very low, and it would be difficult to maintain temperature stability using air cooling. The key issue is that there are limitations in what can be understood about your on-site requirements; it’s only a rough outline. Oh, you could try cooling a heat transfer oil with water, and then use this heat transfer oil to cool the medium you want to cool…… It’s just an idea.
It depends on the temperature to which your oil needs to cool down. For the air cooler, we set a threshold at 60°C; below that temperature, we use water cooling. Your load is very small, and the air cooler is also small. Air cooling has requirements regarding air temperature; a design air temperature must be specified during the design process. Air cooling can use variable-frequency fans to regulate temperature.
Other issues related to the project design have been resolved, so the entire project process is not discussed in detail. Heat transfer oil is used to cool the material; now, another type of heat exchanger is being sought to cool the heat transfer oil. The plan you mentioned has already been discussed; the control engineer said that the lag in temperature regulation at the third level is severe, and it fails to meet the process requirement of within plus or minus 1 degree Celsius, so this plan was rejected.