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Problem 2: Fins Design The TS General Rudder is a diesel electric propulsion plant with two (800 HP each) DC motors. The DC power for the motors is made available by a power conversion system that utilizes six controllable rectifiers (SCR) per motor. Each SCR contributes to 0.1% to the plant's overall inefficiency in the form of heat loss. To prevent any damage to the SCRs and any other electronic equipment in the power conversion panel (PCP) 60F air is constantly forced across fin heat sinks that are on each SCR at an average velocity of 13.52 ft/sec. The design of the fins are below. Part A: (10 Pts) Makearaswation of a possible film temperature (Ul to find your psychometric properties of air and calculate the surface temperature (T.) of the fins. Use a fin efficiency of 1. (A step to check you work at is when you are close to the right to the final h value I had was 3.530 (Btu/BB) Part B: (20 pts) Using the T. you calculated in Part A calculate your Tu. Was this value within 5% of the To value you used? If not recalculate Part A using an EES or derive a set of equations you can use and calculate a Tuvalue that corresponds within 5% of the Trused to calculate T- Part C: (10 Pts) An emergency shutdown was installed where if a single heat sink exceeds 215F the motors would shut down. An air filter was installed on the PCP to help control debris from entering the cabinet. If the filter begins to get dirt, what velocity would the motors trip? What percentage of the original air flow would this be? Problem 3 A question was asked if we lost air flow to the PCP could we have installed a heat sink that could be used to dissipate enough heat the motors could still run at 50% power and the surface temp of the heat sink not exceed 200F? Score Name: Date/Time: / 100 Part A: (20 Pts) If we have to keep the LxWand the height of the heat sink the same due to space limitations and the size of the SCR itself and the supplier's CNC can only make the aluminum fins as thin as 0.08 inches, what would be optimum fin design? i.e. saapt, and n. (I found to be 12 fins) Part B: (10 Pts) Using the design you outlined above, what is the max heat transfer rate the heat sink can achieve before the fin surface is above 200F? How does this compare with the plant's overall power and our goal? Problem 2: Fins Design The TS General Rudder is a diesel electric propulsion plant with two (800 HP each) DC motors. The DC power for the motors is made available by a power conversion system that utilizes six controllable rectifiers (SCR) per motor. Each SCR contributes to 0.1% to the plant's overall inefficiency in the form of heat loss. To prevent any damage to the SCRs and any other electronic equipment in the power conversion panel (PCP) 60F air is constantly forced across fin heat sinks that are on each SCR at an average velocity of 13.52 ft/sec. The design of the fins are below. Part A: (10 Pts) Makearaswation of a possible film temperature (Ul to find your psychometric properties of air and calculate the surface temperature (T.) of the fins. Use a fin efficiency of 1. (A step to check you work at is when you are close to the right to the final h value I had was 3.530 (Btu/BB) Part B: (20 pts) Using the T. you calculated in Part A calculate your Tu. Was this value within 5% of the To value you used? If not recalculate Part A using an EES or derive a set of equations you can use and calculate a Tuvalue that corresponds within 5% of the Trused to calculate T- Part C: (10 Pts) An emergency shutdown was installed where if a single heat sink exceeds 215F the motors would shut down. An air filter was installed on the PCP to help control debris from entering the cabinet. If the filter begins to get dirt, what velocity would the motors trip? What percentage of the original air flow would this be? Problem 3 A question was asked if we lost air flow to the PCP could we have installed a heat sink that could be used to dissipate enough heat the motors could still run at 50% power and the surface temp of the heat sink not exceed 200F? Score Name: Date/Time: / 100 Part A: (20 Pts) If we have to keep the LxWand the height of the heat sink the same due to space limitations and the size of the SCR itself and the supplier's CNC can only make the aluminum fins as thin as 0.08 inches, what would be optimum fin design? i.e. saapt, and n. (I found to be 12 fins) Part B: (10 Pts) Using the design you outlined above, what is the max heat transfer rate the heat sink can achieve before the fin surface is above 200F? How does this compare with the plant's overall power and our goal

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