Q1. Consider a household refrigerator whose interior volume is 0.6 m'and average temperature and pressure in the kitchen are 20°C and 95 kPa, respectively. The refrigerator door is opened an average of 8 times a day, and each time half of the air volume in the refrigerator is replaced by the warmer kitchen air when the door is opened. Air is assumed to be an ideal gas with constant specific heats at room temperature. Also The moisture is condensed at an average temperature of 4°C. Also, the moisture contents of the air in the kitchen and the refrigerator are 0.010 and 0.004 kg per kg of air, respectively, and thus 0.006 kg of water vapor is condensed and removed for each kg of air that enters. If the refrigerator has a coefficient of performance of 1.4 and the cost of electricity is $0.075/ kWh, determine the cost of the energy wasted per year as a result of opening the refrigerator door. The specific heat of air at room temperature is C=1.005 kJ/kg.°C (Table A-2a). Note: The gas constant of air (R) is obtained from Table A-1 and The heat of vaporization of water (ha) at 4°C is obtained from Table A-4.

Q1. Consider a household refrigerator whose interior volume is 0.6 m'and average temperature and pressure in the kitchen are 20°C and 95 kPa, respectively. The refrigerator door is opened an average of 8 times a day, and each time half of the air volume in the refrigerator is replaced by the warmer kitchen air when the door is opened. Air is assumed to be an ideal gas with constant specific heats at room temperature. Also The moisture is condensed at an average temperature of 4°C. Also, the moisture contents of the air in the kitchen and the refrigerator are 0.010 and 0.004 kg per kg of air, respectively, and thus 0.006 kg of water vapor is condensed and removed for each kg of air that enters. If the refrigerator has a coefficient of performance of 1.4 and the cost of electricity is $0.075/ kWh, determine the cost of the energy wasted per year as a result of opening the refrigerator door. The specific heat of air at room temperature is C=1.005 kJ/kg.°C (Table A-2a). Note: The gas constant of air (R) is obtained from Table A-1 and The heat of vaporization of water (ha) at 4°C is obtained from Table A-4.

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

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