Issues with the cooling efficiency of heat exchangers
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I have a question regarding heat exchangers that I’d like to ask everyone: Given a constant heat exchange area of the heat exchanger, as well as constant flow rates of the hot medium and its initial temperature upon entering the heat exchanger, the requirement is to reduce the temperature of the hot medium from 85 degrees Celsius to 70 degrees Celsius, with the lowest temperature being higher than the highest temperature of the cold medium. Logically, given a constant pipe diameter, the greater the flow rate of the cooling medium entering the heat exchanger, the faster the cooling rate should be. However, in practice, when the control valve is adjusted to its full opening (300 t/h), the cooling rate is the same as when the valve is at 60% of its opening (200 t/h, as determined through process operation experiments). The time it takes for the heat medium to drop from 85 degrees Celsius to 70 degrees Celsius is almost the same. Why is this? (The heat medium is circulated.) I would be very grateful if everyone could help answer this question! Is it a problem with the heat transfer drive?
What are the inlet and outlet temperatures of the cooling water at 300 t/h, and what are they at 200 t/h?
Since the heat medium is circulated, its quantity should be fixed, right? What is that quantity?
At the moment, it’s not possible to determine the inlet and outlet temperatures of the cooling water when they vary, so I’m a bit confused. Does the heat exchanger have a maximum cooling capacity, such that once this critical value is reached, the cooling effect remains the same regardless of the amount of cooling water used? So it’s a question about the residence time?
Does the heat exchanger have a maximum cooling capacity, such that once this critical value is reached, the cooling effect remains the same regardless of the amount of cooling water used? So it’s a question about the residence time?