A composite wall consisting of five series layers of matenials with different properties. Layer thickness, thermal conductivity of the layers and temperatures are shown on the figure. Based on Fourier's law for conduction, answer the following questions. 1. What are the main assumptions? 2. Drive an equation to calculate the heat transfer rate through the Composite wall? 3. Draw the thermal circuit through composite wall? 4. What are the value Ti? 5. What are the value Tj? 6. What are the value Tr? Givens: K= 2 Wim. °C K= 1 W/m.°C Ke= 5 W/m. °C Kn= 4 W/m. °C 100°C Ti 25°C Tj Tr в D cmje Acm

A composite wall consisting of five series layers of matenials with different properties. Layer thickness, thermal conductivity of the layers and temperatures are shown on the figure. Based on Fourier's law for conduction, answer the following questions. 1. What are the main assumptions? 2. Drive an equation to calculate the heat transfer rate through the Composite wall? 3. Draw the thermal circuit through composite wall? 4. What are the value Ti? 5. What are the value Tj? 6. What are the value Tr? Givens: K= 2 Wim. °C K= 1 W/m.°C Ke= 5 W/m. °C Kn= 4 W/m. °C 100°C Ti 25°C Tj Tr в D cmje Acm

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter1: Basic Modes Of Heat Transfer

Section: Chapter Questions

Problem 1.3P: 1.3 A furnace wall is to be constructed of brick having standard dimensions of Two kinds of...

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To determine the thermal conductivity of a structural material, a large 15-cm-thick slab of the material is subjected to a uniform heat flux of 2500 W/m2 while thermocouples embedded in the wall at 2.5 cm. intervals are read over a period of time. After the system had reached equilibrium, an operator recorded the thermocouple readings shown below for two different environmental conditions: Distance from the Surface (cm) Temperature (C) Test 1 0 40 5 65 10 97 15 132 Test 2 0 95 5 130 10 168 15 208 From these data, determine an approximate expression for the thermal conductivity as a function of temperature between 40 and 208C.
1.63 Liquid oxygen (LOX) for the space shuttle is stored at 90 K prior to launch in a spherical container 4 m in diameter. To reduce the loss of oxygen, the sphere is insulated with superinsulation developed at the U.S. National Institute of Standards and Technology's Cryogenic Division; the superinsulation has an effective thermal conductivity of 0.00012 W/m K. If the outside temperature is on the average and the LOX has a heat of vaporization of 213 J/g, calculate the thickness of insulation required to keep the LOX evaporation rate below 200 g/h.
Estimate the R-values for a 5-cm-thick fiberglass board and a 2.5-cm-thick polyurethane foam layer. Then, compare their respective conductivity-times-density products if the density for fiberglass is 50kg/m3 and the density of polyurethane is 30kg/m3. Use the units given in Figure 1.31.
A wall of a house is made from two layers of bricks enclosing a layer of insulation. A radiator is positioned to cover the whole internal surface, and used intermittently when the internal temperature is low. The external surface is exposed to the outside air. Which of the following assumptions could be used to identify the relevant reduced form of the conduction equation to find the temperature in the wall. a. Conduction is mainly in two directions. b. Conduction is mainly in one direction. c. The wall properties are homogeneous. d. Steady conditions exist. e. Unsteady conditions exist. f. There is an internal volumetric heat generation in the wall.
Q1. Consider the composite materials shown in figure. 1. Sketch the equivalent thermal resistance. 2. Calculate the heat transfer per unit area of the wall. 3. Determine the temperatures at interface between the layers. Material A k (W/m K) 2.1 B 6.7 C 3.5 T-15 °C C B C 195 1/4 14h-10 W/m² K -T=50 °C HATH 320.0020 30 mm -
(3-5) A composite furnace wall has an inside wall temperature of 1100 C and an outside wall temperature of 38 C. The types of bricks are available as follows: brick k, W/m-k Thickness, cm Max allowable temp, °C 1. 1.45 10.5 2 0.18 5.5 875 3 0.50 7.0 200 The heat loss must not exceed 0.73 kw/ m?. 3. Determine the minimum wall thickness 4. The actual heat loss for (6) 5. The temperature between the last two bricks counting from the inside.
The following graph shows the thermal behavior of 2 kg of a material called Uniandesato undergoing a solid-liquid phase transition. In a container, thermally insulated from the outside, 20 kg of liquid water at a temperature of 80°C are placed. In addition to this, an unknown amount of Uniandesato in a 100% solid state at its melting temperature (10°C) is added. The specific heat of water is 4186 J/kg°C. a) If the system reaches an equilibrium temperature of 60°C, calculate the initial amount of Uniandesato added to the container. b) Calculate the change in entropy during this process and show that it is consistent with the Second Law of Thermodynamics. Hint: Extract the necessary information to solve this problem from the graph.
Please provide accurate answer with proper steps The wall of the furnace is 30.48 mm thick and is insulated from outside. Thermal conductivity of the wall material is 0.1 W/m K and the insulation material is 0.01 W/m K. The furnace operates at 650 0C and the ambient temperature is 30 0 Allowable temperature on the outer side of the insulation is 1000C. Determine the overall heat transfer by conduction per unit area occurring across a furnace wall made from clay. If the air side heat transfer coefficient is 0.4 W/m2 K, calculate the minimum insulation thickness requirement.
-:) Given a tank wall with a thickness of 0.01 m and a thermal conductivity of 0.2 W/m-K. The convective coefficient is 100 and 10 W/m²K for inner and outer surfaces, respectively. An insulation layer with a thermal conductivity of 0.06 W/m-K is used to reduce the heat flux by 90%, If all the parameters are assumed to remain the same, what is the thickness of the insulation layer? (in meter) (a) 0.052 (d) 0.086 (b) 0.012 (e) 0.043 (c) 0.128
2 of 4 I Review I Constants I Periodic Table In this problem you will estimate the heat lost by a typical house, assuming that the temperature inside is Tin = 20°C and the temperature outside is Tout = 0°C. The walls and uppermost ceiling of a typical house are supported by 2 × 6-inch wooden beams (kwood = 0.12 W/(mK)) with fiberglass insulation (kins = 0.04 W/(mK)) in between. The true depth of the beams is actually 5.625 inches, but we will take the thickness of the walls and ceiling to be Lwall = 18 cm to allow for the interior and exterior covering. Assume that the house is a cube of length L= 9.0 m on a side. Assume that the roof has very high conductivity, so that the air in the attic is at the same temperature Part A How much heat per second H (= Q/AT) is lost from the house due to heat conduction? Give your answer in watts, rounding to the nearest 10 W. » View Available Hint(s) Πν ΑΣφ as the outside air. Ignore heat loss through the ground. The effective thermal conductivity of…
A composite wall consisting of five series layers of materials with different properties. Layer thickness, thermal conductivity of the layers and temperatures are shown on the figure. Based on Fourier's law for conduction, answer the following questions. 1. What are the main assumptions? 2. Drive an equation to calculate the heat transfer rate through the Composite wall? 3. Draw the thermal circuit through composite wall? 4. What are the value Ti? 5. What are the value Tj? 6. What are the value Tr? Givens: KA = 2 W/m. °C KB= 1 W/m.°C Kc = 5 W/m. °C Ko= 4 W/m. °C 100°C Ti 25°C Tj Tr A C +2cm + -6 cm 4cm cm
A wall measures (9x3) m2 and it consists of the following layers, the wall has one door and two windows with an area of 1.8 m2 and 3.5 m2, respectively. The wall consists of the following layers: (1) Hard stone of 70 mm thickness and k = 1.7 W/m.°C. (2) Concrete of 200 mm thickness and k = 1.75 W/m.°C. (3) Polystyrene of 50 mm thickness and k = 0.04 W/m.°C. (4) Plaster of 20 mm thickness and k = 1.25 W/m.°C. The inside and outside design conditions are (22°C, 50% RH) , and (7 °C, 90% RH) respectively, and the inside and outside film resistances are 0.12 and 0.03 m2.°C/W, respectively. Calculate the following: (a) Heat loss through the wall (b) Inside wall surface temperature. (c) Heat loss with no insulation, will the water vapor condense on the wall?