Refrigerant-134a is to be cooled by water in a condenser. The refrigerant enters the condenser with a mass flow rate of 6 kg/min at 1 MPa and 70°C and leaves at 35°C. The cooling water enters at 300 kPa and 15°C and leaves at 25°C. Neglecting any pressure drops, determine (a) the mass flow rate of the cooling water required and (b) the heat transfer rate from the refrigerant to water.

Refrigerant-134a is to be cooled by water in a condenser. The refrigerant enters the condenser with a mass flow rate of 6 kg/min at 1 MPa and 70°C and leaves at 35°C. The cooling water enters at 300 kPa and 15°C and leaves at 25°C. Neglecting any pressure drops, determine (a) the mass flow rate of the cooling water required and (b) the heat transfer rate from the refrigerant to water.

Principles of Physics: A Calculus-Based Text

5th Edition

ISBN:9781133104261

Author:Raymond A. Serway, John W. Jewett

Publisher:Raymond A. Serway, John W. Jewett

Chapter17: Energy In Thermal Processes: The First Law Of Thermodynamics

Section: Chapter Questions

Problem 31P: An ideal gas initially at 300 K undergoes an isobaric expansion at 2.50 kPa. If the volume increases...

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An ideal gas initially at 300 K undergoes an isobaric expansion at 2.50 kPa. If the volume increases from 1.00 m3 to 3.00 m3 and 12.5 kJ is transferred to the gas by heat, what are (a) the change in its internal energy and (b) its final temperature?
In a one-shell and two-tube heat exchanger, cold water with inlet temperature of 20°C is heated by hot water supplied at the inlet at 80°C. The cold and hot water flow rates are 5000 kg/h and 10,000 kg/h, respectively. If the shelland- tube heat exchanger has a UAs value of 11,600 W/K, determine the cold water and hot water outlet temperatures. Assume cpc = 4178 J/kg·K and cph = 4188 J/kg·K.
The oil-containing stream enters the counter-flow heat exchanger with a flow rate of 7258 kg / h, and the temperature of the oil stream drops from 393.4 K to 338.9 K. The water flow used to cool the oil flow enters the heat exchanger at 294.3 K and exits at 305.4 K. Calculate the flow rate of the water and the total heat transfer coefficient (U). (Heat exchanger area: 5.11 m2, Cp for oil: 2.01 kJ / kg K and Cp for water: 4.18 kJ / kg K).
An air conditioner with refrigerant-134a as the working fluid is used to keep a room at 23°C by rejecting the waste heat to the outdoor air at 34°C. The room gains heat through the walls and the windows at a rate of 250 kJ/min while the heat generated by the computer, TV, and lights amounts to 900 W. The refrigerant enters the compressor at 400 kPa as a saturated vapor at a rate of 80 L/min and leaves at 1200 kPa and 70°C. Determine (a) the actual COP, (b) the maximum COP, and (c) the minimum volume flow rate of the refrigerant at the compressor inlet for the same compressor inlet and exit conditions.
A counter-flow double-pipe heat exchanger is to heat water from 20°C to 80°C at a rate of 1.2 kg/s. The heating is to be accomplished by geothermal water available at 160°C at a mass flow rate of 2 kg/s. The inner tube is thin-walled and has a diameter of 1.5 cm. If the overall heat transfer coefficient of the heat exchanger is 640 W/m2?K, determine the length of the heat exchanger required to achieve the desired heating.
A heavy hydrocarbon oil which has a Cp = 2.30 kJ/kg.K is being cooled in a heat exchanger from 371.9 K to 349.7 K and flows inside the tube at a rate of 3630 kg/h. A flow of 1450 kg water/hrenters at 288.6 K for cooling and flows outside the tube. If the water has Cpw = 4.187 kJ/kg.K, a.calculate the water outlet temperature and heat transfer area if the overall heat transfer coefficient, U = 340 W/m2.K and the streams are countercurrent. b.Repeat (a) for parallel flow
A test is conducted to determine the overall heat transfer coefficient in a shell-and-tube oil-to-water heat exchanger that has 24 tubes of internal diameter 1.2 cm and length 2 m in a single shell. Cold water (cp = 4180 J/kg·K) enters the tubes at 20°C at a rate of 3 kg/s and leaves at 55°C. Oil (cp = 2150 J/kg·K) flows through the shell and is cooled from 120°C to 45°C. Determine the overall heat transfer coefficient Ui of this heat exchanger based on the inner surface area of the tubes.
The internal energy of a system increases by 1350 J when the system absorbs 1150 J of heat energy at a constant pressure of 1.01 X 105 Pa. By how much does the volume (m3) of the system change?
Cold water (cp = 4180 J/kg·K) enters the tubes of a heat exchanger with 2-shell passes and 20-tube passes at 20°C at a rate of 3 kg/s, while hot oil (cp = 2200 J/kg·K) enters the shell at 130°C at the same mass flow rate and leaves at 60°C. If the overall heat transfer coefficient based on the outer surface of the tube is 220 W/m2·K, determine (a) the rate of heat transfer and (b) the heat transfer surface area on the outer side of the tube.
A shell-and-tube heat exchanger with 2-shell passes and 12-tube passes is used to heat water (cp = 4180 J/kg·K) with ethylene glycol (cp = 2680 J/kg·K). Water enters the tubes at 22°C at a rate of 0.8 kg/s and leaves at 70°C. Ethylene glycol enters the shell at 110°C and leaves at 60°C. If the overall heat transfer coefficient based on the tube side is 280 W/m2·K, determine the rate of heat transfer and the heat transfer surface area on the tube side.
A one-shell and two-tube type heat exchanger has an overall heat transfer coefficient of 300 Btu/h·ft2·°F. The shell side fluid has a heat capacity rate of 20,000 Btu/h·°F, while the tube side fluid has a heat capacity rate of 40,000 Btu/h·°F. The inlet temperatures on the shell side and tube side are 200°F and 90°F, respectively. If the total heat transfer area is 100 ft2, determine (a) the heat transfer effectiveness and (b) the actual heat transfer rate in the heat exchanger.
A two-shell passes and four-tube passes heat exchanger is used for heating a hydrocarbon stream (cp = 2.0 kJ/kg·K) steadily from 20°C to 50°C. A water stream enters the shellside at 80°C and leaves at 40°C. There are 160 thin-walled tubes, each with a diameter of 2.0 cm and length of 1.5 m. The tube-side and shell-side heat transfer coefficients are 1.6 and 2.5 kW/m2·K, respectively. (a) Calculate the rate of heat transfer and the mass rates of water and hydrocarbon streams. (b) With usage, the outlet hydrocarbon-stream temperature was found to decrease by 5°C due to the deposition of solids on the tube surface. Estimate the magnitude of fouling factor.