To design a heat exchanger that efficiently transfers heat between a hot stream of ethanol vapor and a cool stream of water, while maintaining a temperature difference of 5 C between the inlet and outlet of each stream, you can follow these steps:1. Determine the heat transfer requirements: Calculate the heat transfer rate Q required to achieve the desired temperature difference for both fluids. This can be done using the formula Q = m * Cp * T, where m is the mass flow rate, Cp is the specific heat capacity of the fluid, and T is the temperature difference.2. Choose the type of heat exchanger: Select an appropriate type of heat exchanger based on the application and the fluids involved. For this problem, a shell and tube heat exchanger or a plate heat exchanger would be suitable choices, as they are commonly used for liquid-liquid and vapor-liquid heat transfer applications.3. Design the heat exchanger: Determine the required heat transfer area A using the formula Q = U * A * LMTD, where U is the overall heat transfer coefficient and LMTD is the logarithmic mean temperature difference between the hot and cold fluids. The overall heat transfer coefficient U can be estimated based on the properties of the fluids and the materials used in the heat exchanger.4. Optimize the flow arrangement: Choose a flow arrangement that maximizes the heat transfer efficiency while minimizing the pressure drop across the heat exchanger. This can be achieved by selecting the appropriate number of passes, tube layout, and baffle spacing for a shell and tube heat exchanger, or by choosing the right plate arrangement for a plate heat exchanger.5. Minimize fouling and corrosion: Select materials and design features that minimize fouling and corrosion, as these factors can significantly reduce the heat transfer efficiency and the lifespan of the heat exchanger. For example, using stainless steel or other corrosion-resistant materials for the heat exchanger components can help prevent corrosion.6. Validate the design: Perform a thermal and hydraulic analysis of the heat exchanger design to ensure that it meets the required heat transfer rate and pressure drop specifications. This can be done using computational fluid dynamics CFD simulations or by using heat exchanger design software.7. Test and optimize the design: Build a prototype of the heat exchanger and test its performance under real-world conditions. Make any necessary adjustments to the design based on the test results to ensure that the heat exchanger meets the desired performance criteria.By following these steps, you can design a heat exchanger that efficiently transfers heat between a hot stream of ethanol vapor and a cool stream of water, while maintaining a temperature difference of 5 C between the inlet and outlet of each stream.