Concept explainers
An automobile radiator may be viewed as a cross-flowheat exchanger with both fluids unmixed. Water,which has a flowrate of
(a) If the overall heat transfer coefficient is
(b) A manufacturing engineer claims ridges can bestamped on the finned surface of the exchanger,which could greatly increase the overall heattransfer coefficient. With all other conditionsremaining the same and the heat transfer surfacearea determined from part (a), generate a plot ofthe air and water outlet temperatures as a function of Ufor
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Fundamentals of Heat and Mass Transfer
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- Geothermal heat pumps, or water-source heat pumps, are classified as either _____loop or _____loop systems.arrow_forward2- In a heat exchanger, steam of 0.08 bar and a specific steam content of 95% is condensed. 381.6 tons / h cooling water with a temperature of 10 ̊C flows in parallel connected tubers with inner / outer diameter 28/30 mm with a speed of 0.65 m / s. The heat transfer surface of the heat exchanger is 220 m2 and it has a k-value of 2200 W / (m2K) . Assume the specific heat capacity of the water 4.18 kJ / (kg K) and density 1000 kg / m3. The K-value is attributed to the outer mantle surface of the tubes. a) Calculate the outlet temperature of cooling water. b) How many tonnes of steam per hour are condensed? c) Determine the number of tubes and tube lengtharrow_forwardA counterflow heat exchanger is designed to cool 0.65 kg/sec of oil with specific heat Cp=3.4 KJ/kg-K from 150°C to 70°C. Water for cooling, Cp = 4.18KJ/kg-K is available at 20°C and flow rate of 0.6 kg/sec. Calculate the length of a 3.5 cm inside diameter tubing in meters. The overall coefficient of heat transfer is 90 W/m²-K. O 452 O 337 O 543 O 296arrow_forward
- Water enters at 115 ℃ at a rate of 2 kg/s in a double-pipe parallel flow heat exchanger to heat a chemical whose inlet temperature is 20 ℃ and at a rate of 3 kg/s. The overall heat transfer coefficient of the heat exchanger is 1200 W/m2. ℃. The heat transfer surface area of the heat exchanger is 7.8 m2. What is the actual heat transfer rate of the heat exchanger? The specific heats of the water and chemical are given to be 4.18 and 1.8 kJ/kg.℃, respectively. Select one: a. 294 kW b. 315 kW c. 275 kW d. 207 kWarrow_forwardQUESTION 8 Cold water (C, = 4180 J/kg.°C) 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 (C, = 2200 J/kg.°C) 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 300 W/m².°C, determine; i. the rate of heat transfer and ii. the heat transfer surface area on the outer side of the tube.arrow_forwardLiquid water is heated inside the tubes of a shell and tube heat exchanger as shown in the figure below. The inlet temperature is 30 °C and the outlet temperature is 50 °C. The tube inside and outside diamters are 16 mm and 18 mm respectively. The mass flow rate in each tube is 0.25 kg/s. Refrigerant Gas Water Out Water In Refrigerant Liquid Estimate: a) The average velocity in each tube: b) The Reynolds number in each tube: c) The Nusselt Number of the flow inside each of the tubes: m/sarrow_forward
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- C by Water (heat capacity = 4.174 kJ/kg: ° C) at a rate of 10 kg/min is heated from 20 ° C to 60 ° oil that has a specific heat of 1.9 kJ/kg: ° C. The oil enters the shell side of the heat exchanger at 120 ° C and leaves at 70 ° C. The overall heat transfer coefficient is 350 W/m2 · ° C. (a) Use the log mean temperature difference method to calculate the heat exchanger area if a counter flow double pipe heat exchanger is used. (b) Use the effectiveness-NTU method to calculate the heat exchanger area if a counter flow double pipe t heat exchanger is used. (c) Use the log mean temperature difference method to calculate the heat exchanger area if a 2-4 shell and tube heat exchanger is used. (d) Use the effectiveness-NTU method to calculate the heat exchanger area if a 2-4 shell and tube heat exchanger is used.arrow_forward2-b Hot exhaust gases, which enter a finned-tube, cross-flow heat exchanger at 300 °C and leave at 100 °C. are used to heat pressurized water at a flow rate of 1 kg/s from 35 °C to 125 °C. The specific heat of water at the average water temperature is 4197 J/kg. K. The overall heat transfers coefficient based on the gas-side surface area is Un = 100 W/m².K. Determine the required gas-side surface area A, using the LMTD and E-NTU method.arrow_forwardHot exhaust gases are used in a finned-tube cross-flow heat exchanger to heat 2.5 kg/s of water from 35 to 85-C. The gases [cp = 1.09 kJ/kg . °C] enter at 200 and leave at 93°C. The overall heat-transfer coefficient is 180 W/m2 • °C. Calculate the area of the heat exchanger using the LMTD approach.arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage LearningRefrigeration and Air Conditioning Technology (Mi...Mechanical EngineeringISBN:9781305578296Author:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill JohnsonPublisher:Cengage Learning