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A logic chip used in a computer dissipates 3 W of power in an environment at
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HEAT+MASS TRANSFER:FUND.+APPL.
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- What is the difference between internal heat generation and heat transfer in any direction. Thank youarrow_forwardA container used to store ice is made of wood 5.0 cm thick and has an effective area of 12,000 cm2 and thermal conductivity of 0.00027 cal/cm2-sec-°C/cm. How much ice inside the box would be melted each 24-hour day if the outside temperature is 25°C and the temperature inside the box is 5°C.arrow_forwardConsider you have conducted a lab work to analysis the system performance of an air conditioning system. Given that the refrigerant is R-134a. Table below shows the data collection on the 4 main sections of the system. Given that the heat loss from the compressor to the ambient is about 12 kJ/kg, and the ambient air temperature and the refrigerated space temperature are 36 °C and 10 C, respectively. Ignore the heat transfer in all the connecting lines between the components. Low Pressure 3.6 bar High Pressure 16 bar * Accuracy of the temperature measurement is about +1 °C T1 T2 T3 T4 10°C 75°C 44 °C 5 °C (a) Sketch a T-s diagram to show the above process. (b) Calculate the coefficient of performance (COP) of the refrigeration cycle. (c) Conduct the entropy analysis for each major component, and suggest a component that should be redesigned to improve the overall system performance. [2.678, Sgen4-1= 0.007635 kJ/(Kg K), Sgenl-2= 0.066885 kJ/(Kg-K), Sgen2-3= 0.041447 kJ/(Kg K), Sgen3-4=…arrow_forward
- 0.3MW / m3 heat is generated in a 6 cm thick flat wall. One surface of the wall is insulated and the other surface is exposed to an environment of 93C. The convection heat coefficient between the wall and the environment is 570 W / m2C and the heat conduction coefficient for the wall is 21 W / Since it is mC, calculate the maximum temperature (T0) inside the wall (C).arrow_forward1. It is commonly recommended that hot foods be cooled first to room temperature by simply waiting a while before they are put into the refrigerator to save energy. Despite this common sense recommendation, a person keeps cooking a large pan of stew twice a week and putting the pan into the refrigerator while it is still hot, thinking that the money saved is probably too little. The average mass of the pan and its contents is 5-kg. The average temperature of the kitchen is 20°C, and the average temperature of the food is 95°C when it is taken off the stove. The refrigerated space is maintained at 3°C, and the average specific heat of the food and the pan can be taken to be 3.9 kJ/kg-K. If the refrigerator has a coefficient of performance of 1.2 and the cost of electricity is Php 21.59 per kW-hr. Determine how much will be saved a year by waiting for the food to cool to room temperature before putting it into the refrigerator. Ans: Php 170.66 20°C Hot food 5°Carrow_forwardA mother takes the milk to be given to her baby from the refrigerator and pours it into a cylindrical bottle for heating. The height of the milk in the bottle is 10 cm. Then he places the bottle into a large container with hot water at a temperature of 62 ° C. The heat transfer coefficient between hot water and bottle is 130 W / m2.oC. The process of heating the milk from 4 0C to 40 0C is required to be completed within 6 minutes. What should be the diameter of the bottle used? The properties of milk can be equal to the properties of water at the same temperature.arrow_forward
- The inner and outer glasses of a 2-m × 2-m double pane window are at 18°C and 6°C, respectively. If the 1-cm space between the two glasses is filled with still air, determine the rate of heat transfer through the air layer by conduction, in kW.arrow_forwardA large plate of 0.5 m thickness and constant thermal conductivity of k=60 W/m⋅K in which heat is generated uniformly at a rate of 2 kW/cm3. One side of the plate is heavily insulated so that there is no heat loss from the insulated side of the plate. The other side of the plate is exposed to the environment at T∞= 25oC with convection heat transfer coefficient is 20 W/m2⋅K. a) Express the differential equation and the boundary conditions for steady operating conditions. b) Determine the variation of temperature in the plate. c) Find the inner and outer surface temperatures of plate. Shortly very useful.pleasearrow_forwardA window is replaced by a wall with thick insulation. The thermal conductivity of the same area will be decreased to 0.0039 W/m/°C and the thickness will be increased to 16 cm. Determine the rate of heat transfer through this area of 2.16 m2 when the temperature outside is 25 C and the temperature inside is 19 C. What quantity of heat is required to raise the temperature of 450 grams of water from 15°C to 85°C? The specific heat capacity of water is 4.18 J/g/°C. A 12.9 gram sample of an unknown metal at 26.5°C is placed in a Styrofoam cup containing 50.0 grams of water at 88.6°C. The water cools down and the metal warms up until thermal equilibrium is achieved at 87.1°C. Assuming all the heat lost by the water is gained by the metal and that the cup is perfectly insulated, determine the specific heat capacity of the unknown metal. The specific heat capacity of water is 4.18 J/g/°C. Elise places 48.2 grams of ice in her beverage. What quantity of energy would be absorbed by the ice (and…arrow_forward
- A wall of length "L" m and height "H" m is made from a thick bricklayer of 26 cm with thermal conductivity of 0.55 W/mk is subjected to heat transfer due to the outside temperature as 43 °C and inside temperature 24 °C. If the energy loss is 10680 kJ in 9 hours. Determine the Heat transfer rate, Surface Area and Length and Height of the wall, if L = 1.5 H.arrow_forwardA certain system dissipates 250 BTU of heat to the surroundings. If the increase in internal energy is 222,000 ft-lbf, what is the work done? Is it done on or done by the system?arrow_forwardWhile 45 kJ / min heat loss occurs from a room containing air to the environment, work input to the room at a speed of 1.2 kW from computers, TVs and lamps realizes. So what is the change in the energy of the air in the room after 30 minutes?arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning