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Stainless steel ball bearings
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Heat and Mass Transfer: Fundamentals and Applications
- A mixture of chemicals is flowing in a pipe (k = 14 W/m·K, Di = 2.5 cm,Do = 3 cm, and L = 10 m). During the transport, the mixture undergoes anexothermic reaction having an average temperature of 135◦C and a convection heat transfer coefficient of 150 W/m2·K. To prevent any incident of thermal burn, the pipe needs to be insulated. However, there is only enough room to fit a 2.5-cm-thick layer of insulation over the pipe. The pipe is situated in a plant, where the average ambient air temperature is 20◦C and the convection heat transfer coefficient is 25 W/m2·K. Determine the thermal conductivity required to maintain the outside surface temperature at 45◦C or lower.arrow_forwardA long aluminum cylinder (p= 170 lbm/ft3, c= 0.22 Btu/lbm F, k = 140 Btu/h ft F) has a diameter of 3 inches. It initially has a uniform temperature of 600 F. It is suddenly quenched in a water bath for 2 min. The water bath is at 120 F and the convective coefficient is 100 Btu/h ft² F. What is the temperature of the cylinder when it leaves the water bath?arrow_forwardFor bacteriological testing of water supplies and in medical clinics, samples must routinely be incubated for 24 h at 37°C. Peace Corps volunteer and MIT engineer Amy Smith invented a low-cost, low-maintenance incubator. The incubator consists of a foam-insulated box containing a waxy material that melts at 37.0°C interspersed among tubes, dishes, or bottles containing the test samples and growth medium (bacteria food). Outside the box, the waxy material is first melted by a stove or solar energy collector. Then the waxy material is put into the box to keep the test samples warm as the material solidifies. The heat of fusion of the phase-change material is 205 kJ/kg. Model the insulation as a panel with surface area 0.490 m2, thickness 4.50 cm, and conductivity 0.012 0 W/m ? °C. Assume the exterior temperature is 23.0°C for 12.0 h and 16.0°C for 12.0 h. (a) What mass of the waxy material is required to conduct the bacteriological test? (b) Explain why your calculation can be done…arrow_forward
- In an aluminum container weighing 0.30 kg are 0.70 kg of water in thermal equilibrium at a temperature of 70°C. Container and water temperature together cool at a rate of 2.5 K/min. What is the heat flux leaking from the container?arrow_forwardWhat is the heat transfer rate required to condense the water, cool the water vapor, and cool the air?arrow_forwardCalculate delta S when 1 mole of supercooled water at –10oC and 100 kPa is converted into ice at -10oC and 100 kPa. The molar heat capacity at constant pressure (Cm,P) of ice is 37.7 J K-1 mol- 1, and that of supercooled water is 76.1 J K-1 mol-1. The enthalpy of freezing of water is -6004 J mol-1. final answer: -20.54 J K-1arrow_forward
- Steam at 100°C is used to warm 350 g of water contained in a 300 g aluminum container. The initial temperature of the water and aluminum is 20°C and after the steam is added, the equilibrium temperature is 50°C. What mass of steam will be required to accomplish this?Specific Heat of steam = 2010 J/kg- oCSpecific Heat of water = 4186 J/kg- oCSpecific Heat of aluminum = 900 J/kg- oCLatent Heat of Fusion of ice = 3.33 x 10 5 J/kgLatent Heat of Vaporization of water = 2.26 x 10 6 J/kgarrow_forwardIf you add heat of magnitude 800 kJ to a mass of 800g of water originally at a temperature 75 degrees C and the water eventually begins to boil. The latent heat of vaporization of water is 22.6 x 105 J/kg, and its specific heat capacity is 4186 J/kg · K. How much water is left in the container? How much heat does its take to get rid of all the water? How long would it take the water to boil away? Please do fast asaparrow_forwardA piece of chromium steel of length 7.4 cm (density = 8780 kg/m³, K = 50 W/m.K, and Cp = 200 j/kg.K) with mass 1.27 kg, is rolled into a solid cylinder with the same length and heated to a temperature of 600 C and quenched in oi at 36 C. You may take the convective heat rate coefficient between the oil and the cylinder at 280 W/m².K. a) Show that the lumped capacitance system analysis is applicable by calculating the Bi Number b) Find the temperature of the cylinder after 4 min. c) Find the total energy loss during this period. The temperature of the cylinder after 4 min is: The Bi Number is: The total energy loss during this 4 min period is: Choose Choose Choosearrow_forward
- Inside a condenser, there is a bank of seven copper tubes with cooling water flowing in them. Steam condenses at a rate of 0.5 kg/s on the outer surfaces of the tubes that are at a constant temperature of 70°C. Each copper tube is 6-m long and has an inner diameter of 20 mm. Cooling water (Cp=4120 J/kgK) enters each tube at 5°C and exits at 60°C. Determine the average heat transfer coefficient of the cooling water flowing inside each tube and the cooling water mean velocity needed to achieve the indicated heat .transfer rate in the condenser Steam Cooling water flowarrow_forwardThree tons of fish is to be stored at a temperature of -10°C for 24hrs. The product enters the chiller at a temperature of 8°C. The specific heat below and above freezing is 0.41 kcal/kg-C and 0.76 kcal/kg-C respectively and its latent heat of fusion is 51 kcal/kg. If the freezing temperature of the product is -2.2 °C, determine the product load in kcal/hr.arrow_forwardA cylindrical can of pea puree has a diameter of 68.1 mm and a height of 101.6 mm. The can is initially at 29.4°C. 68.1 mm 101.6 mm The cans are vertically stacked in a retort, and steam at 115.6°C is admitted. The heat capacity of the metal wall of the can will be neglected. The properties of pea puree and steam are provided in the following Table: PHYSICAL PROPERTIES OF PEA PUREE STEAM PROPERTIES Thermal Conductivity = k=0.830 W/m- K Temperature = 115.6°C Thermal Diffusivity =a=2.007x107 m/s Heat-transfer coefficient of steam = h, = 4540 W/mKarrow_forward
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