Refrigerators Practice Problems
The coefficient of performance of an ice-making machine is 5 and the power input is 800 W. How much ice can this ice machine theoretically make in one day, starting with water at 30 °C?
A heat pump consumes 4,000 kWh of electrical energy annually and runs on average for 12 hours each day. How much power (P) does it need to run?
You put 500 g of water at 0 °C in an ice-cube tray of a portable ice maker. The ice maker has a coefficient of performance of 3 and uses 240 W of electrical power. How long does it take for water to freeze into ice? Ignore any heat that escapes the ice-cube tray.
The energy efficiency ratio (EER) and coefficient of performance (K) are both used to describe the cooling efficiency of a refrigerator. EER is defined as the ratio of the cooling capacity (in Btu/h) to the electrical power input (in watts). K is defined as the ratio of the heat removal rates (in watts) to the electric power input (in watts). If a refrigerator has K = 6.0, what is its EER?
A refrigerator operates at an efficiency of 60% of the maximum possible value for its temperature range. The inside of the refrigerator is maintained at a temperature of 5℃ while the outside environment is at 25℃. 4.0 L of ethanol at 25℃ are placed in the freezer. If the refrigerator consumes 250 W of electrical power, how long it would take to cool the ethanol from an initial temperature of 25℃ to a final temperature of -10℃ using the given refrigerator.? Ethanol has a specific heat capacity of 2440 J/(kg•K) and a 0.789 g/mL density.
Consider 1 ton is the amount of heat required to melt 1 ton (2000 lb or 910 kg) of ice in 24 hours. A small-scale storage facility has a 2.5-ton refrigeration system with a coefficient of performance (COP) of 2.7. Assuming the refrigeration system operates at its typical performance, what is the rate of heat energy removal from the storage in kilowatts?
A cooling system with a coefficient of performance of 4.2 is used to freeze a liquid weighing 2.0 kg initially at a temperature of 25°C. Determine the amount of heat energy exhausted into the room as the liquid solidifies at -10°C. The specific heat capacity of the liquid is 3.8 J/(g•K), and its heat of fusion is 140 J/g.
An industrial chiller unit absorbs 7.5 × 106 J/min of heat from a process and discharges 9.2 × 106 J/min of waste heat to the environment. Calculate the coefficient of performance (COP) of the chiller unit.