401 Water-Water Turbulent Flow Heat Transfer Objective: This laboratory determines the heat transfer rate, log-mean temp

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401 Water Water Turbulent Flow Heat Transfer Objective This Laboratory Determines The Heat Transfer Rate Log Mean Temp 1 (73.72 KiB) Viewed 28 times

401 Water-Water Turbulent Flow Heat Transfer Objective: This laboratory determines the heat transfer rate, log-mean temperature difference (LMTD), and overall heat transfer coefficient in a counter-flow leat exchanger Procedure: The experimental procedure for this laboratory consists of operating counter-flow heat exchanger using the following steps. 1. Set the cooling water flow control valves for counter-current flow 2. Check that heater tank contains water at the correct level 3. Close the "low flow" control valve and fully open the "high flow.control valve 4. Switch on the "supply" and "heater" switches and set the heater control to a high value 5. Increase the hot water inlet temperature (T.) to about 70°C, then adjust the hot water flow rate to a convenient value approximately 5 L/min (80 g/s) 6. Tum on the cooling water until stable operating conditions are reached with T, at about 70°C 7. Complete the table of "Experimental Data" with five minutes between each data set 8. Turn off "heater" but leave "supply" switch on until the hot water inlet temperature decreases to 50°C 9. Turn off "supply" switch and cooling water flow at all locations Calculation: Equation 1 calculates the total heat transferred to or from each fluid by calculating the mass flow rate and measuring the temperature change of each stream (cold and hot). Equations 2-4 determine the log mean temperature difference for heat exchangers. Equation 6 determines the overall heat transfer coefficient of the system (there is only one U value for the entire system). The value, Qures is determined from the average heat transfer of the hot and cold fluid streams. In addition, specific volume (or density) of water is needed to determine the mass flow rate from the measured volumetric flow rate and the specific heat is needed; determine at which condition (temperature) these properties should be evaluated. 0= mc (T-T.) LMTD (counter-flow) - (AT - AT:) /In(AT/AT:) AT, - - Teodor AT, - Tec- A, -0.0288 m? for this specific heat exchanger Q-U. A. LMTD (6) Please report: 1. Heat transfer rate lost by the hot fluid and gained by the cold fluid and discuss any differences between the 2 rates. 2. Log-mcan temperature difference (LMTD) 3. Overall heat transfer coefficient (U) in this counter-flow heat exchanger 4. Make a graph of the hot and cold water temperatures versus distance of the heat exchanger with the origin being the entrance of the hot water 5. The uncertainty of the heat transferred by the hot water, which depends on the uncertainty of the hot water inlet and outlet temperatures, and the mass flow rate of the hot water. Remember to record the uncertainty of the hot water flow rate during the laboratory experiment and assume the thermocouples and reader have a total uncertainty of +0.5°C. Gemee