How to calculate the heat transfer capacity of a heat exchanger
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Dear experts, how is the heat transfer capacity of a heat exchanger calculated?
The calculation is very simple! It’s all about verification calculations now.
The heat transfer rate of a heat exchanger is typically calculated using the following formula: Q = U * A * ΔT. Where: Q represents the total heat transfer amount (measured in joules or kilowatt-hours), U is the overall heat transfer coefficient (with units of W/(m·K)), A is the heat exchange area (in square meters), and ΔT is the average temperature difference (measured in degrees Celsius or Kelvin). The average temperature difference ΔT can be calculated based on the specific inlet and outlet temperatures of the fluid and the flow configuration (such as convective or counterflow). .
Could you please guide me on the specific formula for calculating the average temperature difference? Thank you
The calculation of the average temperature difference ΔT depends on the flow configuration of the heat exchanger; common configurations include co-current and counter-current flow: 1. Co-current flow: ΔT = ( (T_in1 – T_out2) + (T_out1 – T_in2) ) / 2, where T_in1 and T_out1 are the inlet and outlet temperatures of the fluid on one side, and T_in2 and T_out2 are the inlet and outlet temperatures of the fluid on the other side. 2. Counterflow: ΔT = ( (T_in1 - T_in2) - (T_out1 - T_out2) ) / ln( (T_in1 - T_in2) / (T_out1 - T_out2) ), where ln denotes the natural logarithm function. The choice of average temperature difference formula depends on the specific heat exchanger design and fluid flow pattern. Before using the above formula, it is necessary to determine whether the fluids exchange heat with each other in a convective or counter-current manner. .
Appendix B of GB/T151 provides detailed procedures and formulas