11.21 A concentric tube heat exchanger for cooling lubricating oil is comprised of a thin-walled inner tube of 25-mm diameter carrying water and an outer tube of 45-mmdiameter carrying the oil. The exchanger operates in counterflow with an overall heat transfer coefficient of 60 W/m² - K and the tabulated average properties.To,outToin = 100°COilWaterm, = 0.1 kg/sm, = 0.1 kg/sTw.in = 30°CTw.outPropertiesWaterOilp (kg/m3)Cp (J/kg - K)v (m2/s)k (W/m · K)1000800420019007x 10-71 × 10-50.640.134Pr4.7140(a) If the outlet temperature of the oil is 66°C, determine the total rate of heat transfer and the outlet temperature of the water.(b) Determine the length required for the heat exchanger.

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Answered: 11.21 A concentric tube heat exchanger…

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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A counterflow, concentric tube heat exchanger is designed to heat water from 23 to 80 deg C using hot oil,which is supplied to the annulus at 163 deg C and discharged at 140 deg C. The thin-walled inner tube has a diameter of Di=23 mm and the overall heat transfer coefficient is 500 W/m2. K. The design condition calls for a total heat transfer rate of 3300 W. What is the length of the heat exchanger? Select one: a. 0.49417 b. 1.1269 c. 0.92237 d. 0.6234
Single-shell, two-tube pass heat exchanger with surface area 0.4 m? and overall heat transfer coefficient of 1800 W/m2-K; saturated steam at 110°C condenses on one side while water at a flow rate of 0.35 kg/s enters at 17°C. Calculate (a) Outlet temperature of the water (b) Rate of condensation of steam. cp(water)=4179 J/kg. K. 916 I Thermodynamics TABLE A-4 Saturated water-Temperature table Internal energy, Specific volume, m/kg Enthalpy. KJ/kg Entropy, kJ/kg - K k/kg Sa. Sat Sat. Sat. Sat. Sat. Sat. Sat. liquid, Evap., vapor, Sat. Temp., liquid, liquid, Evap.. liquid, Evap., press. Pst kPa vapor, vapor, vapor, T°C Up he 0.001000 0.001000 0.000 21.019 42.020 2374.9 2374.9 0.001 21.020 42.022 0.0000 9.1556 9.1556 0.0763 0.1511 8.7488 8.8999 0.2245 8.5559 8.7803 0.2965 8.3696 8.6661 0.01 5 10 0.6117 0.8725 1.2281 206.00 147.03 106.32 2360.8 2346.6 2381.8 2388.7 2500.9 2489.1 2477.2 2500.9 2510.1 2519.2 8.9487 9.0249 15 20 0.001000 0.001001 2.3392 0.001002 2332.5 2318.4 2395.5 2402.3…
Water from a natural river source at 22°C and a flow rate of 25,000 kg/s is used as the heat sink for a condenser unit at a large manufacturing company. The condenser consist of 20,000 tubes and is used to condense steam to liquid at 50°C. construction and 20mm nominal diameter. The condenser is a one The tubes are of thin wall shell, two-tube-passes heat exchanger. convective heat transfer coefficient of 11,500 W/m².K on the tube outer surface and the water flowing in the tubes is required to remove heat at a rate of 2 x 10° W. Environmental laws require that the effluent from the condensing unit to the river source should be less than 35°C. Using both the e-NTU and LMTD methods, calculate the outlet temperature of the cooling water and the required tube length per pass. The specification is a Use T =27°C; and for flow through the tubes use, Nu, = 0.023 Re Pr°4
QUESTION 6 En. Karim recently bought a 2-shell passes and 12-tube passes type heat exchanger for his metal factory to reduce the hot oil (cp = 2200 J/kg.K) temperature. The hot oil enters the heat exchanger through the shell passes at 160 °C with a flow rate of 0,2 kg/s. The coolant fluid used to reduce the hot oil temperature is water (cp = 4180 J/kg.K). Water flows through the heat exchanger pipe at 18 °C and at flow rate of 0.1 kg/s. The tube inside the heat exchanger is made of 1.8 cm diameter copper tube and the length is 3 m. If the overall heat transfer coefficient is 340 W/m².K, evaluate and discuss your finding for the following parameters; i. The maximum rate of heat transfer, ii. The actual rate of heat transfer, iii. The outlet temperatures of the water, and iv. The outlet temperatures of the oil.
A dairy farm needs to chill the milk from 39°C (extraction temperature is the same as the cow's body temperature) to at least 12°C for storage by using an existing 4-m long concentric-tube heat exchanger. The inner tube of the heat exchanger is 4 cm in diameter. The milk (density: 1035 kg/m³, specific heat: 3860 J/kg.K) flows into the heat exchanger at a rate of 270 liters per hour. On the cold side, there is a supply of water at 2°C at a rate of 0.23 kg/s. The estimated overall heat transfer coefficient of the heat exchanger is 1084.2 W/m².K. It was measured that the water comes out of the heat exchanger at 11°C. Is the milk indeed being cooled down to at least 12°C by heat exchanger as required by the farm? Looking at the temperatures obtained from your calculation, put an argument whether the heat exchanger is a parallel-flow or a counter-flow heat exchanger. Approximate specific heat of water is 4200 J/kg.K. Neglect radiation.
A shell and tube heat exchanger is designed as a counter flow type. Water (cp = 4182 J/kg.oC) enters the shell side at 30 oC with a mass flow rate of 12.5 kg/s. A mass flow rate of 19.5 kg/s of engine oil (cp = 1060 J/kg.o C), enters the tube side at 300 oC. Each tube is having an inner diameter of 36 mm and a wall thickness of 2 mm, and a length of 3 m. If the heat exchanger effectiveness is 60 %, calculate the following:1. The heat transfer rate,2. The exit temperature for each fluid,
Task 03 B) Double-pipe heat exchangersare used in many industries because of their low design and maintenance costs, flexibility, and low installation cost. They are mainly used for sensible heating or cooling of process fluids in applications of small heat transfer Water at the rate of 68 kg/min is heated from 35 0C to 75 0C by an oil having specific heat of 1.9 kg/kJ.0C . The fluids are used in a counter flow double-pipe heat exchanger, and the oil enters in the exchanger at 175 0C and leaves at 140 0C . The overall heat transfer coefficient is 320 W/m2. 0C . Apply heat transfer formulae to heat exchangers and calculate the heat exchanger area.
Below data was obtained from an experimental activity for a parallel pipe heat exchanger. Arrangement: counterflow (cold fluid in annular and hot fluid in tube). Mass flow rate: - Hot fluid: 1.03 kg/s - Cold fluid: 0.91 kg/s Temperatures: - Hot fluid inlet (Th.1): 80.5 +/- 10% °C - Hot fluid outlet (Th2): 64.0 +/- 10% °C - Cold fluid inlet (Te1): 20.0 +/- 10% °C - Cold fluid outlet (Tc2): 41.0 +/- 10% °C Assume cp constant and equal to 4.2 kJ/kg-K. 1. State assumptions (at least 9 unique ones) and include references. 2. What is the log mean temperature difference in °C? 3. What is the heat transfer rate on the cold side in kW? Heat added or lost on cold side? 4. What is the heat transfer rate on the hot side in kW? Heat added or lost on hot side? 5. What is the effectiveness of the heat exchanger for the given conditions? 6. Calculate the propagation of uncertaintv in kW for part 3 (heat transfer rate on the cold side) and part 4 (heat transfer rate on the hot side).
. The gas turbine operating conditions are: Turbine Exhaust 805 Temperature (°F) Pressure (psia) Flow rate (lbm/hr) Density (lbm/ft³) Specific heat (Btu/lbm °F) 0.259 A cross flow plate fin compact heat exchanger is to be used for this heat recovery application. 16.1 196,000 Compressor Discharge 0.0316 347 132 193,000 0.4380 0.251
Task (1) A. You were asked to design and manufacture a plate heat exchanger, as shown in the figure, to be used in transferring heat from hot water to cold water. Which material (copper, aluminium or polyethylene) will you choose to manufacture the inner plates of the heat exchanger to obtain the highest heat transfer? Give reason for your choice. B. Will the device be lighter in weight if it is made of copper, aluminium or polyethylene? Explain your answer. C. After you completed manufacturing the heat exchanger, you noticed that its outer surface is conductive to electricity, which may be dangerous during operation. what can you do to insulate it? D. Explain two types of degradation that could happen in the heat exchanger and discuss how to prevent them? E. Briefly explain one of the degradation types in polymers.
QUESTION 7 A local brand of water heater has offered a counterflow concentric tube heat exchanger, consisting of thin walled copper drains with a diameter D; = 50 mm. Waste water from the shower enters the heat exchanger at Thi= 38 °C while fresh water enters the room at Te,j= 10 °C. The waste water flows down the vertical drain wall in a thin, falling film and providing h, = 10 kW/m²·K. i. If the annular gap is d = 10 mm, the heat exchanger length is L = 1 m, and the water flow rate is m = 10 kg/min, determine the heat transfer rate and outlet temperature of the warmed fresh water. ii. If a helical spring is installed in an annular gap so the fresh water is forced to flow a spiral path from the inlet to the fresh water outlet, resulting in he = 9050 W/m²-K, determine the heat transfer rate and outlet temperature of the fresh water. iii. Based on the result from Q5(b), calculate the daily saving if 15,000 guests each take 10 minutes shower per day and cost of water heating is…

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