Concept explainers
In a supercomputer, signal propagation delays arereduced by resorting to high-density circuit arrangements which are cooled by immersing them in a specialdielectric liquid. The fluid is pumped in a closed loopthrough the computer and an adjoining shell-and-tubeheat exchanger having one shell and two tube passes.
During normal operation, heat generated within the computer is transferred to the dielectric fluid passing through the computer at a flow rate of
dielectric fluid may be assumed to have constant properties of
(a) If the heat exchanger consists of 72 thin-walled tubes, each of 10-mm diameter, and fully developed how is assumed to exist within the tubes, what is the convection coefficient associated withflow through the tubes?
(b) If the dielectric fluid enters the heat exchanger at
(c) For the exchanger with the tube length per passdetermined in part (b), plot the outlet temperature
of the dielectric fluid as a function of its flow ratefor
(d) The site specialist for the computer facilities isconcerned about changes in the performance of the water chiller supplying the cold water
(e) Repeat the performance analysis of part (d) todetermine the effect of
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Fundamentals of Heat and Mass Transfer
- 11.50 In a supercomputer, signal propagation delays are reduced by resorting to high-density circuit arrange- ments which are cooled by immersing them in a special dielectric liquid. The fluid is pumped in a closed loop through the computer and an adjoining shell-and-tube heat exchanger having one shell and two tube passes. Coolant loop Heat exchanger Computer Two Pump During normal operation, heat generated within the com- puter is transferred to the dielectric fluid passing through the computer at a flow rate of rm, = 4.81 kg/s. In turn, the fluid passes through the tubes of the heat exchanger and the heat is transferred to water passing over the tubes. The dielectric fluid may be assumed to have constant proper- ties of c, = 1040 J/kg • K, µ= 7.65 × 10-4 kg/s•m, k = 0.058 W/m K, and Pr= 14. During normal opera- tion, chilled water at a flow rate of ri, = 2.5 kg/s and an inlet temperature of Twj = 5°C passes over the tubes. The water has a specific heat of 4200 J/kg ·K and provides…arrow_forwardA fuel oil is pumped from a distillation column to two storage tanks. Each tank services a different section of the plant. The pipe contracts from a 500 mm diameter (A) to a 300 mm diameter (B) pipe, and then branches into a two pipe sections, leading to the storage tanks, i.e. one 200 mm (C) diameter and the other, 230 mm diameter (D). The velocity of the fluid exiting the column is 2 m.s-1 and the velocity the fluid exiting the 230 mm pipe is 3 m.s-1 . Calculate the discharges at the exit of both pipes (C and D), and the velocities at the entrance of the branch node (B) and the exit of the 200 mm pipe (C)? A, B, C and can be taken as points in the pipeline system.arrow_forwardHomework: A counterflow heat exchanger is located between a collector and a storage tank. The fluid in the collector side is a water-glycol mixture with cp=3840 J/kg. °C and a flow rate of 1.35 kg/s, whereas the fluid in the tank side is water with a flow rate of 0.95 kg/s. If the UA of the heat exchanger is 5650 W/°C, the hot glycol enters the heat exchanger at 59°C, and the water from the tank at 39°C, a) estimate the heat exchange rate; b) if FRUL is 5.71 W/m².°C and collector area is 16 m², what is the ratio FR/FR?arrow_forward
- For Heat transfer through cylinder tube wall, the temperature is to be a linear function of r (radius) of the tube. Select one: O True O False The conductivity of H20 in solid form (ice) is higher than that of H20 in liquid form (water). Select one: O True O False F, (Correction factor for temperature in some heat exchangers) should be 1.0 or greater than 1.0 in some cases. Select one: O True Falsearrow_forwardAs a process engineer, you are given the task to design a heat exchanger to cool a tank for mixing water and sulfuric acid. Based on the data below, calculate the rate of heat transfer needed to maintain the temperature at 300 K for mixing the following two streams (stream 1 mixed with stream 2). Stream 1: A solution of 25 wt.% sulfuric acid at 300 K flowing at 2 kg/s Stream 2: A solution of 40 wt.% sulfuric acid at 350 K flowing at 1 kg/s Copyright e Meiraw- Education. Permission reguired for reproducton or dapiay 300 200 100 350 K -100 300 K -200 -300 250 -400 -500 10 20 30 40 50 60 Wt. % H,SO, 70 80 90 100 H/kJ (kg solution)arrow_forwardShown below is a heat exchanger used to cool down the liquid in the tube. The shell is well insulated. (2) If inner walls of the shell are system boundaries, and liquids within system boundaries (the liquid between the shell and tube and the liquid in the tube) are chosen as the system, select the correct energy balance equation._____________ A. B. C. D.arrow_forward
- Table Q3 is given to collect the temperature of hot and cold water at the inlet and outlet positions in the laboratory using Tube Heat Exchanger (TD360a) by varying the cold-water flow rate to investigate the effect of cold-water flow rate on the heat exchanger’s performance. (a) Complete all the output parameters indicated in the table given in Appendix 1. (b) Draw the temperature (TH1, TH2, TC1 and TC2) on the vertical vs position (1, 2) on the horizontal axis for each flow and discuss the effect of cold water flow rate change on the exit temperature of both cold water and hot water. (c) Draw the graph of Energy Balance Coefficient and Mean Temperature Efficiency on vertical axis and cold-water flow rate on horizontal axis. Discuss the effect of flow rate on the Energy Balance Coefficient and Mean Temperature Efficiency based on your finding.arrow_forwardPlease solve this Question in 30 minutes i will give you positive feedbackarrow_forward#2 Separate streams of steam and air flow through the turbine and heat exchanger arrangement shown in the figure below, where the air stream mass rate m'5 ranges from 1500 kg/min to 3500 kg/min in increments of 500 kg/min and Wt1= 10,000 kW,. Steady-state operating data are provided on the figure. Heat transfer with the surroundings can be neglected, as can all kinetic and potential energy effects. Steam in 1500 kg/min 2000 kg/min 2500 kg/min Mass Rate of Air M5 in kg/min 3000 kg/min 3500 kg/min Turbine T₁ = 600°C P₁ = 20 bar W₁ T3 T₂=400°C P2 10 bar Temperature T6 = 1200 K P6 = 1 bar tmt tm Heat exchanger TWO TURBINE PROBLEM Py = 10 bar T3 = ? Analyze the two-compressor system for different air mass flow rates into the heat exchanger. Provide clearly detailed professional written sample of the calculations needed to analyze each component of the system and the overall system. Complete the following table and plot the mass of air M5 against the Temperate T3, plot the mass rate M5…arrow_forward
- 6. In an heat exchanger of parallel flow type, water enters at 60°C and leaves at 80°C while oil of specific gravity 0.8 enters at 250°C and leaves at 100°C. The specific heat of oil is 2.5 kJ/kg K and surrounding temperature is 300 K. Determine the loss in availability on the basis of one kg of oil flow per second. [Ans. – 59.9 kJ]arrow_forwardAn automobile radiator is a compact heat exchanger powered by water-air. In both fluids does not interfere. There are 60 pipes with an inner diameter of 6.35 mm in the radiator. Of each pipe its length is 800 mm. Hot water enters the pipe at 85 ° and leaves at 55 ° C. Water flow 0.8 kg / s given as. The air enters the winged surfaces diagonally at 10 ° C and heats up to 35 ° C. emerges from the other side. Find the total heat transfer coefficient of the air side of the pipe.arrow_forward2.arrow_forward
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