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ChE Lab 4 Exp. B
Transcript of ChE Lab 4 Exp. B
Meriel Van Vliet
Tony Spitznagel Purpose To Demonstrate: The working principles of a tube heat exchanger operating under parallel and counter flow conditions
The effect of hot water temperature variation on the performance characteristics of a concentric tube heat exchanger
The effect of flow rate variation on the performance characteristics of a concentric tube heat exchanger operating under counter flow conditions
Industrial Applications Most common type of heat exchanger in oil refineries and other large chemical processes Suited for higher-pressure applications Error Discussion Random Errors
Manual temperature readings
Ambient heat loss
Bubble in cold water supply
Sensitive valve controls
Contaminated hot water
Hot water inlet temperature inconsistancy Procedure Theory Shell and tube heat exchangers used to transfer heat from high temperature streams to low temperature streams
Increasing flow rates and varying temperatures has an effect on heat transfer
Increasing flow rates
Increasing hot water inlet temperature
Part 3 Effect of varying temperatures Temperatures selected
70C Average energy transfer efficiency Mean temperature efficiency Efficiency did not seem to be effected by this small temperature range
Flow rate and heat transfer area seem to control efficiency
Part 4 Effect of Flow Goal: To investigate the effect of flow rate on heat exchanger properties.
Counter-current arrangement: cold water flow rate steady, hot water flow rate varied.
Increasing flow rate increases the turbulence of the fluid.
Increased turbulence usually leads to more heat transfer More heat is transferred at higher flow rates.
At higher flow rates, both cold and hot streams exit warmer than at lower flow rates.
Heat Transfer Coefficient Increases with flow rate Part 1 •Inlet/Outlet at the same location for hot and cold water
•Initial higher temperature difference of hot/cold causes largest amount of heat transfer. (highest temperature gradient)
•As temperatures get close to each other at the outlet, there is less heat transfer.
•If given enough length, hot and cold would approach an equilibrium temperature.
Goal: To investigate the behavior of co-current flow heat transfer in a heat exchanger Part 2 Goal: To investigate the behavior of counter-current flow heat transfer in a heat exchanger •Inlet for hot is outlet for cold, and vice versa, same flow rates as co-current.
•Near constant heat gradient
•Allows cold stream to keep getting warmer instead of settling towards an equilibrium temperature.
•Cold stream at same inlet T as co-current will end at a higher temperature, thus recovering more heat.
•If given enough length, cold stream temp. can approach initial hot stream temp.
Raising temperature will increase heat transferred Goal: To investigate the effect of changing the temperature on heat exchanger properties Counter-current arrangement: cold water temperature steady, hot water temperature varied.
-flow rates held constant Conclusions Counter-current configuration transfers more heat than co-current
Increasing hot water inlet temperature results in greater overall heat transfer
- No conclusions can be made regarding effect on heat transfer coefficient
Increasing flow rate improves heat transfer
- The data indicates that heat transfer coefficient increases with flow, despite the
Use water as the fluid in a shell and tube heat exchanger
-Investigate co-current setup
-Investigate counter-current setup
-Investigate effect of varying temperatures
-Investigate effect of varying flow rates Higher flow rates result in higher turbulence, resulting in more heat transfer Heat transfer coefficient vs. temperature Heat transfer coefficient vs. flow rate Temperature as a function of position Equations to Support Theory Cold water temperature increase comparison:
co-current: 16.1 °C
counter-current: 18.1 °C