A composite wall is made up of 10 cm of common brick against 15cm of concrete with 1.5 cm of plaster on inside of wall. Assume still air in room at 25 °C. The outside air at 40 °C the wind velocity is 25 km/hr. Note: Use standard tables for values of thermal conductivities and film co-efficient. Find: a) The thermal resistance of wall b) The overall heat transfer cop-efficient. c) The steady state heat transfer rate per unit area of wall d) Heat transfer if the outside and inside film resistances are disgraded.

A composite wall is made up of 10 cm of common brick against 15cm of concrete with 1.5 cm of plaster on inside of wall. Assume still air in room at 25 °C. The outside air at 40 °C the wind velocity is 25 km/hr. Note: Use standard tables for values of thermal conductivities and film co-efficient. Find: a) The thermal resistance of wall b) The overall heat transfer cop-efficient. c) The steady state heat transfer rate per unit area of wall d) Heat transfer if the outside and inside film resistances are disgraded.

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.

Chapter4: Numerical Analysis Of Heat Conduction

Section: Chapter Questions

Problem 4.46P

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A composite wall is made up of 10 cm of common brick against 15cm of concrete with 1.5 cm of plaster on inside of wall. Assume still air in room at 25 °C. The outside air at 40 °C the wind velocity is 25 km/hr. Note: Use standard tables for values of thermal conductivities and film co-efficient. Find: a) The thermal resistance of wall b) The overall heat transfer cop-efficient. c) The steady state heat transfer rate per unit area of wall d) Heat transfer if the outside and inside film resistances are disgraded
Suppose city 1 leaves an entire block (100 mm ×× 100 mm) as a park with trees and grass (emissivity 0.96) while city 2 paves the same area over with asphalt (emissivity 1.0). Sunlight heats each surface to 41.5 ∘C∘C by sunset, and then the surface radiates its heat into a cube of air 100 mm on a side and at 30.0 ∘C∘C. If each city block maintains the same radiated power for 2.1 hh and there are no other energy losses, what is the final temperature of the cube of air above the block in city 1? The density of air at 30.0 ∘C∘C is 1.16 kg/m3kg/m3. Express your answer to three significant figures and include appropriate units. If each city block maintains the same radiated power for 2.1 hh and there are no other energy losses, what is the final temperature of the cube of air above the block in city 2? The density of air at 30.0 ∘C∘C is 1.16 kg/m3kg/m3. Express your answer to three significant figures and include appropriate units.
A computer is protected against impact by foam packaging (spring stiffness, k = 100 N/cm; mass, m = 11 kg, including packaging). The maximum acceleration that the computer can withstand on impact with a hard surface is 4g. At the maximum acceptable impact acceleration, how much does the packaging compress upon impact? Give the answer in cm. What is the maximum height, h, in cm that the case can fall from without damaging the computer?
Hi any help with thsi question would be great as im struggling a bit - the final answer should be a) 2.413 MN in the negative x-direction and b)6.97MN Any notes on the method next to calcs would be much appreciated. Thankyou! a)Find the net resultant horizontal force on the wall if it is 10m long (into page), the density of seawater p= 1025 kg/m3, acceleration due to gravity = 9.81m/s2 h1=4m and h2=8m b) find the net resultant vertical force when the density of the wall p=2400kg/m3. The wall is 10m long (into the page), g=9.81 h1=8m and h2=8m
Completely solve and box the final answer. Write legibly 1. How much heat will be transferred in KW if a hot gas at 175ºC crosses a wall 100-mm thick and cross-sectional dimensions of 25 cm x 52 cm. It leaves the wall at 52ºC. The thermal conductivity of the wall is 12.4 W/m-ºK?
After the sinking of RMS Titanic, US operated the International Ice patrol with the purpose of monitoring the presence and movements of icebergs in the Atlantic and Arctic oceans. Once, they observed a unique tabular iceberg in a form of a rectangle (250 km x 50 km x 300 m). How many years would it take to melt the iceberg solely by heat from the sun if the ice absorbs a mean of 98 J/m2 -s, 12.5 hrs per day? Note: the exposed area for heating is 250 km x 50 km and the density is 920 kg/m3 . This is my solution.
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A thermo-pane window consisting of 2 pieces of glass 0.4 cm thick and an air gap of 0.75 cm has inside temperature of 68 F and outside of 95 F. a) Compute the rate of heat lost b) find the the temperature spread across the single piece of glass.
Two thermal reservoirs are connected by a solid copper bar. The bar is 2 m long, and the temperatures of the reservoirs are 80.0∘C and 20.0∘C. a) Suppose that the bar has a constant rectangular cross section, 10 cm on a side. What is the rate of heat flow through the bar? b) Suppose the bar has a rectangular cross section that gradually widens from the colder reservoir to the warmer reservoir. The area A is determined by A=(0.01m^2)[1.0+x/2.0m] , where x is the distance along the bar from the colder reservoir to the warmer one. Find the rate of heat flow and the rate of change of temperature with distance at the colder end, at the warmer end, and at the middle of the bar.
At 250C, the interfacial tension between water and n – octyl alcohol is 8.50 dyne/cm. if the surface tension of n-octyl is 27.53 dyne/cm and that of the water is 72.75 dyne/cm, predict whether water spreads on the alcohol by calculating a) Work of cohesion of n-octyl b) Work of adhesion and c) the spreading coefficient of water on the alcohol. Will alcohol spread on water?
solve step by step and correctly. A family enters a winter vacation cabin has been unheated for such a long time the interior temperature is the same as the outside temperature (00C). The cabin consists of a single room of floor area 4m by 4m and height 3m. The room contains one 2kW electric heater. Assuming that the room is perfectly airtight and that all the heat from the electric heater is absorbed by the air, none escaping through the walls or being absorbed by the furnishing, how long after the heater is turned on will the temperature reach the comfort level of 240C.
From an open water surface with air temperature 22°C, relative humidity is 40% and wind speed is 3 m/s, all measured at height 2 m above the water surface. Assume a roughness height of 0.03 cm. The net radiation is 200 W/m^2. Cp=1005 J/kg-K *Kelvin = Degree Celsius + 273.2 , use this in computing for the density of air A. Calculate the evaporation using Priestley-Taylor Method (mm/day) B. Calculate the air density (kg/cu.m.)