Question

Write an interactive computer program that will give the effectiveness of a heat exchanger and the outlet temperatures of both the hot and cold fluids when the types of fluids, the inlet temperatures, the mass flow rates, the heat transfer surface area, the overall heat transfer coefficient, and the type of heat exchanger are specified. The program should allow the user to select from the fluids water, engine oil, glycerin, ethyl alcohol, and ammonia. Assume constant specific heats at about room temperature.

Short answer

Answer: The effectiveness of a heat exchanger is the ratio of the actual heat transfer between the fluids to the maximum possible heat transfer, represented by ε = (Q_actual / Q_max). It can be used along with the actual heat transfer (Q_actual) and the inlet temperatures of the hot and cold fluids to calculate the outlet temperatures of the hot and cold fluids in the heat exchanger using the following equations: ε = (T_out_c - T_in_c)/(T_in_h - T_in_c) ε = (T_in_h - T_out_h)/(T_in_h - T_in_c)

Step-by-step solution

Understand the problem and gather required data

To solve this problem, first, we need to understand the concept of heat exchanger effectiveness and gather the required data, such as specific heat values for each fluid (water, engine oil, glycerin, ethyl alcohol, and ammonia) at room temperature.

Calculate heat exchanger effectiveness

The effectiveness of a heat exchanger (ε) can be calculated using the following formula: ε = (Q_actual / Q_max) where Q_actual is the actual heat transfer between the fluids and Q_max is the maximum possible heat transfer.

Calculate the actual heat transfer (Q_actual)

The actual heat transfer (Q_actual) can be determined using the following formula: Q_actual = m_c * C_p_c * (T_out_c - T_in_c) = m_h * C_p_h * (T_in_h - T_out_h) where m_c and m_h are the mass flow rates of the cold and hot fluids, C_p_c and C_p_h are the specific heat capacities of the cold and hot fluids, and T_in_c, T_out_c, T_in_h, and T_out_h are the inlet and outlet temperatures of the cold and hot fluids, respectively.

Calculate maximum possible heat transfer (Q_max)

The maximum possible heat transfer (Q_max) can be calculated using the following formula: Q_max = U*A*ΔT_m where U is the overall heat transfer coefficient, A is the heat transfer surface area, and ΔT_m is the logarithmic mean temperature difference between the hot and cold fluids.

Calculate the outlet temperatures

The outlet temperatures T_out_c and T_out_h can be determined using the effectiveness of the heat exchanger (ε) and the actual heat transfer (Q_actual) by solving the following equations: ë = (T_out_c - T_in_c)/(T_in_h - T_in_c) ë = (T_in_h - T_out_h)/(T_in_h - T_in_c) These equations can be solved analytically or numerically for a given set of input values. To design an interactive computer program, these calculations can be implemented using any programming language. The user inputs for the fluid types, inlet temperatures, mass flow rates, heat transfer surface area, overall heat transfer coefficient, and the type of heat exchanger must be requested, and then the effectiveness of the heat exchanger and the outlet temperatures for both hot and cold fluids can be calculated accordingly.