Concept explainers
Consider the knee space shown in Fig. 5-11. The vertical dimension is 8 ft, the horizontal dimension is 3 ft, and the space is 20 ft long. The walls and roof surrounding the space all have an overall heat-transfer coefficient of about
Want to see the full answer?
Check out a sample textbook solutionChapter 5 Solutions
HEATING, VENTILATING,+AC ANAL...EBOOK>I<
Additional Engineering Textbook Solutions
Automotive Technology: Principles, Diagnosis, And Service (6th Edition) (halderman Automotive Series)
Statics and Mechanics of Materials (5th Edition)
Foundations of Materials Science and Engineering
Thermodynamics: An Engineering Approach
Manufacturing Engineering & Technology
HEAT+MASS TRANSFER:FUND.+APPL.
- A 2.5-m-tall steel cylinder has a cross-sectional area of 1.5 m2. At the bottom, with a height of 0.5 m, is liquid water, on top of which is a 1-m high layer of gasoline, relative density of 0.8. The gasoline surface is exposed to atmospheric air at 101 kPa. What is the gage pressure at the liquid interface? what is the answer? a.0.077 atm b.15.839 psi c. 1.139 mmHg d.108.848 kPaarrow_forwardYou are designing an enclosure which houses a PCB. Mounted outside the enclosure on its top is a set of aluminum fins, as seen in the sketch below. The enclosure (and fins) are 150mm deep long. There is no forced airflow. Neglect the thickness of the enclosure walls. Neglect heat transfer out of the sides and bottom of the enclosure. If the PCB produces 4000 W/m2: a) Most industrial-grade ICs have a maximum temperature of 85oC. If you must keep your PCB below this what is the maximum thermal resistance from the PCB to the air surrounding the fins? Assume the air around the fins stays at room temperature. b) If the top of the enclosure (and bottom of the fin base) runs at 50°?, what is the effective thermal conductivity above the PCB? Hint: Because the air inside the enclosure is trapped and heats up, any air properties NOT given below are calculated at the average air temperature (T1+T2)/2. c) What is the temperature at the base of the fins? d) What is the efficiency of the fins? e)…arrow_forward(a) The temperature at the surface of the heating rod, T1. (b) If the salt solution temperature is 300 degree Celcius, what is the value of convection heat transfer coefficient, h of the salt solution ? (c) If the heating rod is not covered by metallic cylinder and corresponds to the result of part (a) and (b), how much the rate of energy transfer to the salt solution ? (d) Compare and discuss the difference of heat transfer with and without the matallic cylinder.arrow_forward
- Sipho’s mother is making a fire in the stove inside a shack using coal. A fan is used to extract the flue gasfrom the fire via a chimney made of zinc material. The wall thickness of Chimney is L=4mm and the walltemperature of the chimney on the flue gas side is T_si=60˚C. Sipho, playing outside next to the chimneyexperiences an ambient temperature of 20˚C. The surrounding temperature is T_sur=35˚C and the emissivityis ε=0.95. Assume the convection coefficient is 20W/m2K and the chimney is grey material.Under these conditions determine the outer surface (air side) temperature T_so=? of the chimney.arrow_forwardHi, can you help me with the following problem? A thermally insulated tank of water 2 m x 2 m, depth 1 m is stirred with a paddle for threehours. If the paddle is driven by a motor whose shaft power is 8 kW determine the rate ofchange of temperature in degrees C per hr and the increase in temperature of the water.The specific heat of water is 4200 J/kgC. Identify a system and start your analysis from anappropriate form of the Fist Law of Thermodynamicsarrow_forwardH.W: 10-02-2021: The exterior wall of a building consists of 100 mm thick face brick (k = 0.9 Wm¯'K'), 40 mm thick polystyrene insulating board (k 0.036 Wm'K¯), 125 mm thick concrete block (k = 1.8 Wm¯'K') and 15 mm thick interior gypsum board (k = 0.18 Wm K). The inside and outside convective heat transfer coefficients are 6.5 Wm K and 22.5 Wm K respectively. The outside air temperature is -5°C and the inside air temperature is 20°C. The wall is 3 m high and 15 m long. Calculate (i) the rate of heat loss through the wall,arrow_forward
- What is the rate of heat transfer through a piece of Celotex 3 ft by 8 ft by 1 in. in thickness, if the temp of one surface is 80°F and of the other side is 60°F? thermal conductivity of Celotex in AES = 0.028. Pls determine the temperature gradient and the direction of the heat transfer as well.arrow_forwardAnswer this ASAP The diameter of the tube is 25 mm. The specific heat of water is 4.18 kJ/kg. °C. The overall heat transfer coefficient is 0.7 kW/m².°C. 1.Cmin 2.Maximum heat transfer rate 3.Heat transfer surface areaarrow_forwardA cylindrical storage tank with diameter of 4m and a length of 10 m will hold a fluid whose temperature must be maintained at 347k. in order to size the heater required for the tank the following worst-case scenario is considered: Ambient temperature=-20 wind speed=20m/s tank wall temperature=347k what size (kW) heater will be needed?arrow_forward
- Q1-A block as sphere made of Teflon initially at a temperature of 90 C is suddenly immersed in a fluid at 20 C. The convection heat- transfer coefficient is 15 W/m2 C. Determine the dimension of the block that it is just considered as lumped-capacity system. Calculate : (1) the time the center of the sphere reaches the half value of initial temperature and, (2) the heat loss from the block at that time.arrow_forwardA camera used for monitoring marine life is placed in water where T.. -5°C and the convection heat transfer coefficient h=1420 W/m²K. The camera is operating, but its battery is experiencing thermal runaway, causing the camera to become very hot, and there is volumetric heat generation, qe inside it. There is no heat generation within the waterproof, protective enclosure surrounding it. 00:08 The camera is already compromised; however, its owner hopes to save the protective case. Each interface (between layers A and B and between layers B and C) must not exceed a temperature of 185°C, or these plastic, protective layers will begin to melt. Approximate the camera and its casing as a composite, rectangular object with flat surfaces. The device's total thickness, L=LA + 2LB +Lc, is much smaller than its area (into the page); therefore, 1-D conduction can be approximated through the layers. On the left surface of layer A, the temperature is measured to be T₁ = 8.0°C, and the temperature on…arrow_forwardHeat Transfer Problem 1arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning