A blood warmer is to be used during the transfusion of blood to a patient. This device is to heat blood taken from the blood bank at
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Introduction to Heat Transfer
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- 5. Steam condensing on the outer surface of a thin-walled circular tube of 50 mm diameter and 6 m length maintains a uniform surface temperature of 100 C. Water flows through the tube at a rate of m= 0.25 kg/s, and its inlet and outlet temperatures are Tmi = 15 C and Tmo = 57C. What is the average convection coefficient associated with the water flow? Data: Pvater = 1000 kg/m³ ; c, = 4.2 kJ/kg-K.arrow_forwardFor 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_forwardMerrill et al. (1965) in a series of classic experiments studied the flow of blood in capillary tubes of various diameters. The blood had a hematocrit of 39.3 and the temperature was 20°C. They measured the pressure drop as a function of the flow rate for five tube diameters ranging from 288 to 850 μm. When they expressed the measured pressure drops in terms of the wall shear stress, and the volumetric flow rates in terms of the reduced average velocity, all of the data for the various tube sizes formed, within the experimental accuracy, a single line as predicted by the Rabinowitsch equation expressed in terms of reduced average velocity. From their results they provide the following values of the Casson parameters at 20°C: τy = 0.0289 dynes cm−2 and s = 0.229 (dynes s cm−2)1/2. Using these values for τy and s, show that the equation below for reduced average velocity provides an excellent fit to their data summarized in the following table. (Wall shear stress) τw , dynes cm-2…arrow_forward
- When can the conductive thermal resistance of the tube in a heat exchanger be neglected in overall heat transfer coefficient calculation? Never When the tube is thin or the material is highly conductive When the tube is thin. When the tube material is highly conductive. Which of the following sentence(s) is/are true? We cannot calculate thermal resistance of a solid slab. Thermal resistance concept is applicable only in Cartesian or Cylindrical coordinate. We cannot calculate thermal resistance of a solid cylinder. To apply thermal resistance concept, a problem only needs to be one dimensional and steady.arrow_forwardIn the final stages of production, a pharmaceuticalis sterilized by heating it from 30°C to 75°C as it moves at0.2 m/s through a straight thin-walled stainless steeltube of 12.7-mm diameter. A uniform heat flux is maintained by an electric resistance heater wrappedaround the outer surface of the tube. If the tube is 10 m long, what is the required heat flux? If fluidenters the tube with a fully developed velocity profile and a uniform temperature profile, what is thesurface temperature at the tube exit? Fluid properties may be approximated as ? = 1000 kg/m3, cp =4000 J/kg K, ? = 2 x 10-3 kg/s m, k = 0.8 W/m K, and Pr = 10.arrow_forwarda. An air stream passing through a 2-inch (1/6 ft) diameter, thin-walled tube is to be heated by high- pressure steam condensing on the outer surface of the tube at 320 °F. The overall heat transfer coefficient, h between steam and air can be assumed to be 25 Btu/(ft2.hr °F) with the air entering at 100 ft/sec, 10 psia, 40 °F. The air is to be heated to 150 °F. Determine the tube length required. Assuming Rayleigh Line flow, calculate the static pressure change due to heat addition. Also, for the same inlet conditions, calculate the pressure drop due to friction, assuming Fanno flow in the duct with f = 0.018. b. c. d. To obtain an approximation to the overall pressure drop in this heat exchanger, add the two results. Discuss the accuracy of this calculation.arrow_forward
- 1. A 5 x 5 cm plate is at a constant temperature of 50 ° C and tilted 60 ° to the horizontal. Calculate the heat released by both sides of the plate to the water at 20 ° C. (Only free convection is heat transfer). 2. The cross flow type heat exchanger has 40 pipes with a diameter of 1 cm. The heat exchanger is 1 x 1 meter in size. Cold water (Cp 4180 J / kg ° C) enters the pipe with a temperature of 18 ° C and an average speed of 3 m / s. hot air as a heat exchanger with a temperature of 130 ° C and an average speed of 12 m / s and a pressure of 105 kPa (cp = 1010 J / kg ° C). if the coefficient of total heat is 130 W / m² ° C calculate: A. temperature out of the air and air b. Heat rate that occursarrow_forwardThe thermal conductivity of aluminum is higher than that of concrete material (one of most popular building materials). Select one: O True O False An example of convective heat transfer is freezing of the ground during the winter. Select one: O True O False Fouling on heat exchanger tubes has no effect on heat exchanger's performances. Select one: O True O False For good winter jackets, they should be made of light-weight materials, filled with air, that have very low conductivity. Select one: O True O Falsearrow_forwardA square isothermal chip is of width 5mm on a side mounted in a substrate such that its side and back surfaces are well insulated, while the front surface is exposed to the flow of coolant at 15C. From reliability considerations, the chip temperature must not exceed 85C. If air is used as a coolant, h = 200W/m2. If a dielectric liquid is used as coolant, h = 3000W/m2. What is the difference in maximum allowable power through the chip between the two coolants? (answer in W) *arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning