How to reverse-engineer the overall heat transfer coefficient of a heat exchanger?
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It is known that the cold stream in the heat exchanger consists of water at a flow rate of 18.7 m3/h; its temperature rises from 35°C to 162°C under a pressure of 65 bar； The hot stream consists of 18.7 m3/h of water and 535 kg/h of nitrogen, and it is cooled from 186.5°C to 60°C at a pressure of 63 bar. What is the actual overall heat transfer coefficient of the heat exchanger? How to simulate and solve it? ? ?
To determine the overall heat transfer coefficient (U) of a counterflow heat exchanger, the following steps are usually required: 1. **Obtain basic data**: Determine parameters such as the temperature, flow rate, and pressure of the cold stream and the hot stream. It is known that the cold stream is water, while the hot stream includes water and nitrogen. 2. **Calculate heat exchange**: - Determine the required heat based on the flow rate and temperature rise of the cold stream: \ Where \(\dot{m}_c\) is the mass flow rate of the cold stream, \(C_{pw}\) is the specific heat capacity of water, and \(T_{c,out}\) and \(T_{c,in}\) are the outlet and inlet temperatures of the cold stream, respectively. 3. **Heat lost by the heat flow**: A similar calculation is performed on the heat flow to determine the amount of heat lost by it: Note that the specific heat capacity of nitrogen must be looked up in a table. 4. **Verify heat balance**: Ensure \(Q_c = Q_h\). 5. **Determine the logarithmic temperature difference**: \ 6. **Calculate the overall heat transfer coefficient U**: \ where A is the heat exchange area of the heat exchanger. 7. **Simulation-based solution**: Fluid dynamics software (such as ANSYS, COMSOL) can be used for simulation. By setting boundary conditions and material properties, simulations can be run to observe the heat exchange process and determine the U value. By following the above steps, the actual overall heat transfer coefficient of the heat exchanger can be determined. .
I want you to ask for the heat exchange area!
You can calculate it using Aspen EDR or htri!
Given that the heat exchange area is 600 m2, I want to determine whether the actual overall heat transfer coefficient is consistent with that specified during design
Q=K A ΔT, where K is