Questions about heat exchangers
Thread Content
We have a heat exchanger where the hot material inlet was originally 123 degrees and the outlet was 49 degrees.； The cold material (water) inlet is 23 degrees and the outlet is 33 degrees. Now we have raised the inlet temperature to 103 degrees, but the outlet has only dropped to 47 degrees (the water temperature has basically remained unchanged). What is going on?
Q=ΔT* F * KQ=G * Cp（T1-T2）Q: Heat exchanger W ΔT: Logarithmic temperature difference ℃ F: Heat exchange area m2 K: Heat transfer coefficient W/(m2 * ℃)G: Material mass flow Kg/s Cp: Material specific heat capacity KJ/(Kg * ℃) T1: Material inlet temperature ℃ T2: Material outlet temperature ℃ The inlet temperature of the heat exchanger material decreases, making the logarithmic temperature difference smaller. ； Other parameters have not changed, the heat transfer coefficient of the heat exchanger has not changed, and F, K, G, and Cp are fixed values. The Q value will inevitably decrease, so (T1-T2) will shrink, resulting in little change in the final outlet temperature.
The person upstairs is so professional. To put it simply, the circulating cold water temperature is 23 degrees and the outlet temperature doesn’t have much room to drop.
The analysis above is more professional. I think it means that the heat transfer driving force is small, resulting in insignificant temperature changes! !
The analysis on the second floor is too professional. I think that the difference between the circulating water temperature and the hot material outlet temperature is small, and there is basically no room for reduction.