An electric car travels at a constant highway speed of 60 mph, requiring a battery current...
An electric car travels at a constant highway speed of 60 mph, requiring a battery current draw of 50 A. The cooling system operates such that the average convection coefficient, h, is 25 W/m2 K. The coolant average temperature is 23°C. Suddenly a cooling system malfunction results in a decrease of the convection coefficient to 5 W/m2K. The pack has a heat transfer surface area of 1.2m2 and a mass of 50 kg. The pack specific heat is 600J/kg K and the total pack internal resistance is 0.1 ohm. The following should be answered analytically and not using any simulation solutions to the governing equations. Will the pack reach its upper safe operating limit of 60°C? If so, how long will it take to reach this value? If not, what is the maximum temperature the pack will reach? Assume ambient temperature to be 28°C.
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An electric car travels at a constant highway speed of 60 mph,
requiring a battery current...
9. (7 pts) A pack with a total internal resistance of 0.5 ohm experiences a constant...
9. (7 pts) A pack with a total internal resistance of 0.5 ohm experiences a constant current draw of 50 amps, for which the pack temperature is 40°C. Suddenly the pack experiences a rise in current demand to a constant 200 amps. Estimate the time it takes for the pack to reach 60°C. Assume a lumped temperature distribution and a coolant temperature of 30°C. The pack mass is 100 kg and the cell specific heat is 800 J/kg K.
8. A battery pack with a total internal resistance of 1 ohm delivers 100 amps under...
8. A battery pack with a total internal resistance of 1 ohm delivers 100 amps under steady state conditions. The pack is cooled with water. a. (3 pts) Estimate the mass flow rate of water required to keep the water temperature change from inlet to exit within 5°C. b. (3 pts) The cooling flow arrangement results in an average convection coefficient of 200 W/m2K. Estimate the temperature of a cell close to the water exit, where the water temperature is...
be clear Problem 3 (60 Points). A 1-2 shell-and-tube heat exchanger must be designed to heat...
be clear
Problem 3 (60 Points). A 1-2 shell-and-tube heat exchanger must be designed to heat 2.5 kg/s of water from 15 to 85°C. The heating is to be accomplished by passing hot engine oil at a rate of 5.2 kg/s, which is available at 160°C, through the shell side of the exchanger. The oil is known to provide an average convection coefficient of 400 W/m2K on the outside of the tubes. Ten tubes passes the water through the shell....
11. A forced convection system like that used in the lab has been reconfigured for steady-state o...
11. A forced convection system like that used in the lab has been reconfigured for steady-state operation. The solid copper rod is heated with an embedded resistor, and allowed to reach steady state at various input powers. Wind tunnel air velocity and temperature are kept constant throughout the experiment series. A table of input power versus temperature is provided, as well as key system characteristics Compute the convection coefficient experienced by the cylinder in this flow condition. (a) 69.62W/(K-m2) (b)...
Required information A shell-and-tube heat exchanger is used for cooling 47 kg/s of a process stream...
Required information A shell-and-tube heat exchanger is used for cooling 47 kg/s of a process stream flowing through the tubes from 160°C to 136°C. This heat exchanger has a total of 100 identical tubes. each with an inside diameter of 2.5 cm and negligible wall thickness. The average properties of the process stream are: p = 950 kg/m”, k = 0.50 W/mK, Cp=3.5 kJ/kg.K, and -20 mPas The coolant stream is water (cp=4.18 kJ/kg K) at a flow rate of...
2. A nuclear fuel rod with diameter of D=40 mm and length L=1m, has properties of...
2. A nuclear fuel rod with diameter of D=40 mm and length L=1m, has properties of k=1 W/mK, c=1600J/kg-K, and p=400 kg/m² (a)Heat is generated uniformly in the rod with q'"' = 2 x 106 W/m. The rod is first cooled in oil with constant temperature To= 400 K and average heat transfer coefficient h=50 W/m2K. Under steady state, determine the surface temperature of the rod Ts. (10 pts) (b)Now the heat generation in the rod is stopped, where q"'...
2. A nuclear fuel rod with diameter of D=40 mm and length L=1m, has properties of...
2. A nuclear fuel rod with diameter of D=40 mm and length L=1m, has properties of k=1 W/mK, c=1600J/kg-K, and p=400 kg/m² (a)Heat is generated uniformly in the rod with q'"' = 2 x 106 W/m. The rod is first cooled in oil with constant temperature To= 400 K and average heat transfer coefficient h=50 W/m2K. Under steady state, determine the surface temperature of the rod Ts. (10 pts) (b)Now the heat generation in the rod is stopped, where q"'...
Problem 4: Heat Exchangers Analysis (25 points) A counterflow plate-type heat exchanger as shown in the...
Problem 4: Heat Exchangers Analysis (25 points) A counterflow plate-type heat exchanger as shown in the figure below is used to cool propane fuel W 50 mm H 25 mm Saturated Vapor propane Thickness t =5 mm H 25 mm Cooling water Length L The flow rate of the cooling water is 0.2 kg/s, while the flow of the propane is 0.1 kg/s. The water enters the heat exchanger at a temperature of 20°C while the propane enters at its...
2. A nuclear fuel rod with diameter of D=40 mm and length L=1m, has properties of...
2. A nuclear fuel rod with diameter of D=40 mm and length L=1m, has properties of k=1 W/mK, c=1600J/kg.K, and p=400 kg/m3. (a)Heat is generated uniformly in the rod with q'"' = 2 x 106 W/m3. The rod is first cooled in oil with constant temperature To= 400 K and average heat transfer coefficient h=50 W/m2K. Under steady state, determine the surface temperature of the rod Ts. (10 pts) (b)Now the heat generation in the rod is stopped, where q'''...
A nuclear fuel rod with diameter of D=40 mm and length L=1m, has properties of k=1...
A nuclear fuel rod with diameter of D=40 mm and length L=1m, has properties of k=1 W/ mK, c=1600J/kg.K, and p=400 kg/mº. (a)Heat is generated uniformly in the rod with q'"' = 2 x 10 W/m. The rod is first cooled in oil with constant temperature Tu= 400 K and average heat transfer coefficient h=50 W/m2K. Under steady state, determine the surface temperature of the rod Ts. (10 pts) (b)Now the heat generation in the rod is stopped, where q'"'...
9. (7 pts) A pack with a total internal resistance of 0.5 ohm experiences a constant current draw of 50 amps, for which the pack temperature is 40°C. Suddenly the pack experiences a rise in current demand to a constant 200 amps. Estimate the time it takes for the pack to reach 60°C. Assume a lumped temperature distribution and a coolant temperature of 30°C. The pack mass is 100 kg and the cell specific heat is 800 J/kg K.
8. A battery pack with a total internal resistance of 1 ohm delivers 100 amps under steady state conditions. The pack is cooled with water. a. (3 pts) Estimate the mass flow rate of water required to keep the water temperature change from inlet to exit within 5°C. b. (3 pts) The cooling flow arrangement results in an average convection coefficient of 200 W/m2K. Estimate the temperature of a cell close to the water exit, where the water temperature is...
be clear
Problem 3 (60 Points). A 1-2 shell-and-tube heat exchanger must be designed to heat 2.5 kg/s of water from 15 to 85°C. The heating is to be accomplished by passing hot engine oil at a rate of 5.2 kg/s, which is available at 160°C, through the shell side of the exchanger. The oil is known to provide an average convection coefficient of 400 W/m2K on the outside of the tubes. Ten tubes passes the water through the shell....
11. A forced convection system like that used in the lab has been reconfigured for steady-state operation. The solid copper rod is heated with an embedded resistor, and allowed to reach steady state at various input powers. Wind tunnel air velocity and temperature are kept constant throughout the experiment series. A table of input power versus temperature is provided, as well as key system characteristics Compute the convection coefficient experienced by the cylinder in this flow condition. (a) 69.62W/(K-m2) (b)...
Required information A shell-and-tube heat exchanger is used for cooling 47 kg/s of a process stream flowing through the tubes from 160°C to 136°C. This heat exchanger has a total of 100 identical tubes. each with an inside diameter of 2.5 cm and negligible wall thickness. The average properties of the process stream are: p = 950 kg/m”, k = 0.50 W/mK, Cp=3.5 kJ/kg.K, and -20 mPas The coolant stream is water (cp=4.18 kJ/kg K) at a flow rate of...
2. A nuclear fuel rod with diameter of D=40 mm and length L=1m, has properties of k=1 W/mK, c=1600J/kg-K, and p=400 kg/m² (a)Heat is generated uniformly in the rod with q'"' = 2 x 106 W/m. The rod is first cooled in oil with constant temperature To= 400 K and average heat transfer coefficient h=50 W/m2K. Under steady state, determine the surface temperature of the rod Ts. (10 pts) (b)Now the heat generation in the rod is stopped, where q"'...
2. A nuclear fuel rod with diameter of D=40 mm and length L=1m, has properties of k=1 W/mK, c=1600J/kg-K, and p=400 kg/m² (a)Heat is generated uniformly in the rod with q'"' = 2 x 106 W/m. The rod is first cooled in oil with constant temperature To= 400 K and average heat transfer coefficient h=50 W/m2K. Under steady state, determine the surface temperature of the rod Ts. (10 pts) (b)Now the heat generation in the rod is stopped, where q"'...
Problem 4: Heat Exchangers Analysis (25 points) A counterflow plate-type heat exchanger as shown in the figure below is used to cool propane fuel W 50 mm H 25 mm Saturated Vapor propane Thickness t =5 mm H 25 mm Cooling water Length L The flow rate of the cooling water is 0.2 kg/s, while the flow of the propane is 0.1 kg/s. The water enters the heat exchanger at a temperature of 20°C while the propane enters at its...
2. A nuclear fuel rod with diameter of D=40 mm and length L=1m, has properties of k=1 W/mK, c=1600J/kg.K, and p=400 kg/m3. (a)Heat is generated uniformly in the rod with q'"' = 2 x 106 W/m3. The rod is first cooled in oil with constant temperature To= 400 K and average heat transfer coefficient h=50 W/m2K. Under steady state, determine the surface temperature of the rod Ts. (10 pts) (b)Now the heat generation in the rod is stopped, where q'''...
A nuclear fuel rod with diameter of D=40 mm and length L=1m, has properties of k=1 W/ mK, c=1600J/kg.K, and p=400 kg/mº. (a)Heat is generated uniformly in the rod with q'"' = 2 x 10 W/m. The rod is first cooled in oil with constant temperature Tu= 400 K and average heat transfer coefficient h=50 W/m2K. Under steady state, determine the surface temperature of the rod Ts. (10 pts) (b)Now the heat generation in the rod is stopped, where q'"'...
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