a) A basement refrigerator is used to store cool beverages during the long hot summer. The refrigerator is maintained at 2°C and the ambient basement temperature is 20°C. Glass bottles filled with cola at 25°C are placed in the refrigerator. Each bottle weighs 0.20 kg and there is 0.25 kg of cola in each bottle. Assume the glass bottles are in thermal equilibrium with the cola at all times (i.e. the temperature of the bottles and cola are equal). The available energy (work) to cool the bottles of cola in the refrigerator space is 110 kJ. The coefficient of performance of the refrigerator is 0.20 % of that of a Carnot refrigerator. Assume the bottle has the properties of plate glass, and the cola has the properties of saturated liquid water. How many bottles containing cola can be placed in the refrigerator and cooled to 2°C? b) Define the reversible (Q /Q)rev ratio in terms of T, and T. Prove that the coefficient of performance of a reversible heat pump (). is IH TH-TL rev

a) A basement refrigerator is used to store cool beverages during the long hot summer. The refrigerator is maintained at 2°C and the ambient basement temperature is 20°C. Glass bottles filled with cola at 25°C are placed in the refrigerator. Each bottle weighs 0.20 kg and there is 0.25 kg of cola in each bottle. Assume the glass bottles are in thermal equilibrium with the cola at all times (i.e. the temperature of the bottles and cola are equal). The available energy (work) to cool the bottles of cola in the refrigerator space is 110 kJ. The coefficient of performance of the refrigerator is 0.20 % of that of a Carnot refrigerator. Assume the bottle has the properties of plate glass, and the cola has the properties of saturated liquid water. How many bottles containing cola can be placed in the refrigerator and cooled to 2°C? b) Define the reversible (Q /Q)rev ratio in terms of T, and T. Prove that the coefficient of performance of a reversible heat pump (). is IH TH-TL rev

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter3: Transient Heat Conduction

Section: Chapter Questions

Problem 3.12P

See similar textbooks

Similar questions

The tip of a soldering iron consists of a 0.6-cm- diameter copper rod, 7.6 cm long. If the tip must be 204C, what are the required minimum temperature of the base and the heat flow, in watts, into the base? Assume that h=22.7W/m2KandTair=21C.
A Block has the potential to produce up to 3000 MWh of geothermal energy when the project is developed to completion. In the region, the average geothermal temperature gradient is 20 °C/km, the maximum depth that can be reached using conventional drilling technology is 10 km, the average annual surface temperature is 25 °C and the rock under the surface in that region has a density of 2600 kg/m3 and a specific heat of 1000 J/kg.K. Determine the minimum mass of rock required to meet this demand.
An iron block cools down from 200°C to the room temperature of 27°C,when outdoor is 5°C, heating the room. Determine the maximum theoreticalamount of heat that can be supplied to the house as the iron cools down to27°C.
A classroom type room with 45students taking an exam in thermodynamics is expected to release a body heat of about 8kJ/hr per person. In order to compensate this heat dissipation, an air-conditioning unit is to be installed. If specific heat capacity and density of air is 1.0062kJ/kg-K and 1.2kg/m3, determine the volume of air flow required in examination room if the air is to be cooled down from 290C to 200C. a. 8.5177Li/s b. 9.1262Li/s c. 9.2022Li/s d. 9.0501Li/s
In determining the average rate of heating of a tank of 20% sugar syrup, thetemperature at the beginning was 20°C and it took 30 min to heat to 80°C. Thevolume of the sugar syrup was 50 ft3 and its density 66.9 lb/ft3. The specific heat ofthe sugar syrup is 0.9 Btu lb-1°F-1.(a) Convert the specific heat to kJ kg-1°C-1.(b) Determine the rate of heating, that is the heat energy transferred in unit time, in SI units (kJ s-1)
A large punch bowl holds 3.99 kg of lemonade (which is essentially water) at 20.5 °C. A 0.0550-kg ice cube at -10.2 °C is placed inthe lemonade. What are the final temperature of the system, andthe amount of ice (if any) remaining? Ignore any heat exchangewith the bowl or the surroundings.
Air is contained in a piston cylinder arrangement shown in the figure. Initially the air is200 kPa and 20 oC while the piston rests on the lower stops. The air is heated, and thepiston starts to rise freely when the pressure reaches 250 kPa until the piston start toencounter a linear spring when the volume is doubled. Heat is further added until the airtemperature reaches 1000 oC when the volume is triple the initial volume. Considering airas ideal gas:a- What is the final pressure?b- Find the specific work done during the whole process.c- Draw the process on a p-v diagram indicating the properties at all states
2) Two glass bulbs, one on the left with a volume of 2 liters and the other on the right with avolume of 6 liters, are connected to one another by a thin tube that is initially closed by astopcock. The bulb on the left has 0.1 moles of ideal gas, and the bulb on the right isevacuated. The system is in thermal equilibrium with the surroundings at 300K. When thestopcock is opened, the gas flows out to fill both bulbs. Calculate A for this process. If wewere to insert a propeller to extract work as the gas flows from left to right, what is themaximum amount of work that we could possibly extract?
3.0 kg of steam at a pressure of 100 kPa are contained in a rigid sealed tank of volume 5.95 m3. The steam begins to cool as heat is transferred to the atmosphere. When the internal pressure reaches 10 kPa, the tank walls will collapse.a) What is the initial temperature of the steam in the tank (in oC)?b) What will the temperature be in the tank when the walls collapse (in oC)?c) Attheinstantofcollapse,whatisthemassofwaterinthevapourandliquidstate (in kg)?d) Deduce the work done for this process
Discuss the application of the first law of thermodynamics to a mountaineer who eats food, gets warm and perspires a lot during a climb, and does a lot of mechanical work in raising herself to the summit. The mountaineer also gets warm during the descent. Is the source of this energy the same as the source during the ascent?
THARMOFLUID A student living in a 3-m X 4-m X 4-m dormitory room turns on her 100-W fan before she leaves the room on a summer day, hoping that the room will be cooler when she comes back in the evening. Assuming all the doors and heat trans windows are tightly closed and disregarding any heat fer let through the walls and the windows, determine the temperature in the room when she comes back 8 h later. Use specific heat values at room temperature, and assume room to be at 100 kPa and 20°C in the morning she leaves.
THERMOFLUID A student living in a 3-m X 4-m X 4-m dormitory room turns on her 100-W fan before she leaves the room on a summer day, hoping that the room will be cooler when she comes back in the evening. Assuming all the doors and heat trans windows are tightly closed and disregarding any heat fer let through the walls and the windows, determine the temperature in the room when she comes back 8 h later. Use specific heat values at room temperature, and assume room to be at 100 kPa and 20°C in the morning she leaves.