1- If Q(cold) is 22 W, and Q(hot) is 92 W, what is the refrigerator's efficiency?(give...
1- If Q(cold) is 22 W, and Q(hot) is 92 W, what is the refrigerator's efficiency?(give as a fraction)
2- A building surface of 46 m2 is exchanging heat by convection with the air wind at 300 K. If the surface is at 400 K what is the rate of heat transfer in kW?
(Air heat transfer coefficient, h, is 15 W/(m2 K))
(zero decimals and include units)
3- A house gains 387 MJ of heat during the day (8 hours). If the room temperature is reasonably maintained by a 7-kW air conditioner what is the COP of the unit?
(express result with one decimal and no units)
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1- If Q(cold) is 22 W, and Q(hot) is 92 W, what is the
refrigerator's efficiency?(give...
please answer all 10 questions! Question 1 If the refrigerator's efficiency is 61.7% and Q(cold) is...
please answer all 10 questions! Question 1 If the refrigerator's efficiency is 61.7% and Q(cold) is 935 W, what is Q(hot) in kW? Question 2 Find the net radiative energy exchange (W) when: the area of radiative surface is 68 m^2, surface emissivity is 0.49, the cold temp is 433 K, and the hot temp. is 534 K. Question 3 Consider a device where the minimum input is 18, the actual input is 62, and the ideal output is 49....
If the refrigerator's efficiency is 12% and Q(cold) is 927 W, what is Q(hot) in kW?
If the refrigerator's efficiency is 12% and Q(cold) is 927 W, what is Q(hot) in kW?
Cold conditioned air at 10°C is flowing inside a 1.5 cm thick square aluminum (k = 240 w/mK) duct...
Cold conditioned air at 10°C is flowing inside a 1.5 cm thick square aluminum (k = 240 w/mK) duct of inner cross section of 25x25cm at a mass flow rate of 1.0 kg/s. The duct is exposed to air at 35°C with a combined convection-radiation heat transfer coefficient of 15 W/m2K. The convection heat transfer coefficient at the inner surface is 75 W/.m2.K. If the air temperature in the duct should not increase by more than 1°C determine the maximum...
The wall of a heat exchanger separates hot water at Tin 90 C with h." 80 w/m2.K from cold water a...
The wall of a heat exchanger separates hot water at Tin 90 C with h." 80 w/m2.K from cold water at Tout 10 C with h,ut 60 W/m2.K. The thermal conductivity of the heat exchanger is 180 W/m.K To extend the heat transfer area, two-dimensional ridges are machined on the cold side of the wall. This geometry causes non-uniform thermal stresses, which may become critical for crack initiation along the lines between two ridges. To predict thermal stresses, the temperature...
.0 W/m2-K, including the effec An anaerobic digester cover has an overall heat transfer coefficient U...
.0 W/m2-K, including the effec An anaerobic digester cover has an overall heat transfer coefficient U of 1.0 W/m2.K, including the effects of convection and radiation. The cover has a surface area of 325 m2. The temperature inside the digester is 33°C and the outside air temperature is 0.0°C. What is the rate of heat loss from the digester through the cover? Report your answer in kW, to the nearest 0.1 kW, without entering the units.
2.) A plane wall is made of brick with a thermal conductivity of 1.5 W/(m-K). The...
2.) A plane wall is made of brick with a thermal conductivity of 1.5 W/(m-K). The wall is 20 cm thick and has a surface area of 10 m2. One side of the wall is exposed to outside air blowing against the wall resulting in a heat transfer coefficient of 20 W/(m2-K). The other side is exposed to an air-conditioned room with a convective heat transfer coefficient of 5 W/(m2-K). a. What are the thermal resistances corresponding to conduction through...
A thermocouple is used to measure the temperature of hot air flowing in a duct whose...
A thermocouple is used to measure the temperature of hot air flowing in a duct whose walls are maintained at Tw = 500 K. The thermocouple shows a temperature reading of Tt h = 850 K. Assuming the emissivity of the thermocouple junction to be 0.6, and the convection heat transfer coefficient to be 60 W/m2 · K, (a) draw the thermal resistance network, and (b) determine the actual temperature of the air.
3.9 e wind chill, which is experienced on a cold indy day, is related to increased...
3.9 e wind chill, which is experienced on a cold indy day, is related to increased heat transfer from exposed human skin to the surrounding atmosphere. Consider a layer of fatty tissue that is 3mm thick and whose intenor surface is maintained at a temperature of 36°C. On a calm day the convection heat traneper coefficient at the exter surface is 25 W/m²K, but with 30km/h winds it reaches 65 W/m²K In both cases the ambient air temperature is -15°C....
value 12.50 points 1 out of 3 attempts Hot air at 85°C is blown over a...
value 12.50 points 1 out of 3 attempts Hot air at 85°C is blown over a 1.9-mx 3.9-m flat surface at 21°C. If the convection heat transfer coefficient is 51 W/㎡.oC, determine the rate of heat transfer from the air to the plate. kW
“A pipe is carrying hot water through a cold storage facility. The ambient air in the...
“A pipe is carrying hot water through a cold storage facility. The ambient air in the cold storage has temperature of ?5?C. To maintain uniform temperature in the cold storage, blowers installed in the facility induce a 3 m/s velocity to the cold air (which can be assumed to be flowing across the water pipe). Hot water inside the pipe has a mean velocity of 0.5 m/s. The internal and exter- nal diameter of the pipe are 8.4 cm and...
Cold conditioned air at 10°C is flowing inside a 1.5 cm thick square aluminum (k = 240 w/mK) duct of inner cross section of 25x25cm at a mass flow rate of 1.0 kg/s. The duct is exposed to air at 35°C with a combined convection-radiation heat transfer coefficient of 15 W/m2K. The convection heat transfer coefficient at the inner surface is 75 W/.m2.K. If the air temperature in the duct should not increase by more than 1°C determine the maximum...
The wall of a heat exchanger separates hot water at Tin 90 C with h." 80 w/m2.K from cold water at Tout 10 C with h,ut 60 W/m2.K. The thermal conductivity of the heat exchanger is 180 W/m.K To extend the heat transfer area, two-dimensional ridges are machined on the cold side of the wall. This geometry causes non-uniform thermal stresses, which may become critical for crack initiation along the lines between two ridges. To predict thermal stresses, the temperature...
.0 W/m2-K, including the effec An anaerobic digester cover has an overall heat transfer coefficient U of 1.0 W/m2.K, including the effects of convection and radiation. The cover has a surface area of 325 m2. The temperature inside the digester is 33°C and the outside air temperature is 0.0°C. What is the rate of heat loss from the digester through the cover? Report your answer in kW, to the nearest 0.1 kW, without entering the units.
2.) A plane wall is made of brick with a thermal conductivity of 1.5 W/(m-K). The wall is 20 cm thick and has a surface area of 10 m2. One side of the wall is exposed to outside air blowing against the wall resulting in a heat transfer coefficient of 20 W/(m2-K). The other side is exposed to an air-conditioned room with a convective heat transfer coefficient of 5 W/(m2-K). a. What are the thermal resistances corresponding to conduction through...
3.9 e wind chill, which is experienced on a cold indy day, is related to increased heat transfer from exposed human skin to the surrounding atmosphere. Consider a layer of fatty tissue that is 3mm thick and whose intenor surface is maintained at a temperature of 36°C. On a calm day the convection heat traneper coefficient at the exter surface is 25 W/m²K, but with 30km/h winds it reaches 65 W/m²K In both cases the ambient air temperature is -15°C....
value 12.50 points 1 out of 3 attempts Hot air at 85°C is blown over a 1.9-mx 3.9-m flat surface at 21°C. If the convection heat transfer coefficient is 51 W/㎡.oC, determine the rate of heat transfer from the air to the plate. kW
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