Heating Ventilating and Air Conditioning: Analysis and Design
6th Edition
ISBN: 9780471470151
Author: Faye C. McQuiston, Jeffrey D. Spitler, Jerald D. Parker
Publisher: Wiley, John & Sons, Incorporated
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Chapter 5, Problem 5.22P
Determine the overall heattransfer coefficient for (a) an ordinary vertical single-glass window with thermal break. (b) Assume the window has a roller shade with a
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1. A composite furnace wall is made up of a 12-in. lining of magnesite refractory brick, a 5-in.thickness of 85% magnesia, and a steel casing 0.10-in. thick. Flue gas temperature is 2200 F andthe boiler room is at 80 F. Gas side film coefficient is 15 Btu/hr-sq.ft-F and air side is 4.0.Determine:a. The thermal current Q/Ab. Interface temperaturesc. Effect on thermal current and inside refractory wall temperature if the magnesia insulation weredoubled.
(a) Find the refrigeration capacity if no insulation is used for the walls and ceiling.
(b) Select insulation(s) for the wall and ceiling to reduce the refrigeration capacity.
Evaluate the thickness required for the insulation you selected to reduce the
refrigeration load by approximately 30%.
(c) Add a 1m x 1m window glass to the room. Use the data collected from previous parts.
Assume the internal surroundings surfaces (e.g., walls and ceilings) have the same
temperature as the inside temperature, and the external surroundings (landscape,
buildings, etc.) are also at the same temperature as the outside temperature. Assume
the convection coefficients between air (internal and external) and the glass are the
same as the walls and the air. If the glass has an emissivity of 0.9, calculate the rate of
heat loss through the glass. Assume steady-state conditions, negligible temperature
gradients in the glass, and both inner and outer surfaces exposed to large
surroundings.
A composite wall is formed of a 2.5 cm copper plate, a 3.2 mm layer of asbestos,and a 5 cm layer of fiberglass. The wall is subjected to an overall temperaturedifference of 560oC. Calculate the heat flux through the composite structure.
Chapter 5 Solutions
Heating Ventilating and Air Conditioning: Analysis and Design
Ch. 5 - Determine the thermal conductivity of 4 in. (100...Ch. 5 - Compute the unit conductance C for 512 in. (140...Ch. 5 - Compute the unit thermal resistance and the...Ch. 5 - What is the unit thermal resistance for an inside...Ch. 5 - Compute the thermal resistance per unit length for...Ch. 5 - Assuming that the blocks are not filled, compute...Ch. 5 - The partition of Problem 5-4 has still air on one...Ch. 5 - The pipe of Problem has water flowing inside with...Ch. 5 - Compute the overall thermal resistance of a wall...Ch. 5 - Compute the overall heat-transfer coefficient for...
Ch. 5 - Estimate what fraction of the heat transfer for a...Ch. 5 - Make a table similar to Table 5-4a showing...Ch. 5 - Estimate the unit thermal resistance for a...Ch. 5 - Refer to Problem 5-13, and estimate the unit...Ch. 5 - A ceiling space is formed by a large flat roof and...Ch. 5 - A wall is 20 ft (6.1 m) wide and 8 ft (2.4 m) high...Ch. 5 - Estimate the heat-transfer rate per square foot...Ch. 5 - A wall exactly like the one described in Table...Ch. 5 - Prob. 5.19PCh. 5 - Compute the overall heat-transfer coefficient for...Ch. 5 - Compute the overall heat transfer for a single...Ch. 5 - Determine the overall heattransfer coefficient for...Ch. 5 - A basement is 2020ft(66m) and 7 ft (2.13 m) below...Ch. 5 - Estimate the overall heat-transfer coefficient for...Ch. 5 - Rework Problem 5-23 assuming that the walls are...Ch. 5 - A heated building is built on a concrete slab with...Ch. 5 - A basement wall extends 6 ft (1.8 m) below grade...Ch. 5 - A 2440ft(7.312.2m) building has a full basement...Ch. 5 - The floor of the basement described in Problem...Ch. 5 - Assume that the ground temperature tg is 40 F (10...Ch. 5 - Use the temperatures given in Problem 5-30 and...Ch. 5 - A small office building is constructed with a...Ch. 5 - A 100 ft length of buried, uninsulated steel pipe...Ch. 5 - Estimate the heat loss from 100 m of buried...Ch. 5 - A large beverage cooler resembles a small building...Ch. 5 - Consider the wall section shown in Fig. 5-10. (a)...Ch. 5 - A building has floor plan dimensions of 3060ft....Ch. 5 - Compute the temperature of the metal roof deck of...Ch. 5 - Consider the wall section shown in Fig. -4a,...Ch. 5 - Consider the knee space shown in Fig. 5-11. The...Ch. 5 - Estimate the temperature in an unheated basement...
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- A-For a general office room, the exposed wall (with a window, outside winter type) construction is 19 mm plaster outside (cement and sand) and 20 cm brick (building). The area of the window is 50% of the exposed wall. Calculate the heating load required for the office caused by the wall and window. Take Tout-5 °C and Tin-25 °C, exposed wall height=3 m and width=5 m, Inside and outside still air thermal resistance fi= 9.37 W/m²°C and fo= 34.1 W/m2 °C respectively. (6 marks)arrow_forwardBuild a spreadsheet to do the step by step method for estimating the temperature of unprotected steel work exposed to the ASTM E119 Standard Fire. Assume a convective heat transfer coefficient of 25 W/m2K and an emissivity of 0.5. Assume the specific heat to remain constant at 600 J/kgK. Use a time step of 30 seconds and an ambient temperature of 20°C. Provide an Excel plot showing the curves of the fire and a steel member through a time of 60 minutes with F/V ratios of: a)25 m-1 b)100 m-1 c)200 m-1 d)300 m-1 Note your plot should contain 5 curves. One for the fire and one for each of the F/V values. Also on the spreadsheet, highlight in green, the cells identifying the temperature of the unprotected steel member with an F/V of 200m-1 at the following times: a)3 minutes b)10 minutes c)20 minutes d)50 minutesarrow_forwardRecent studies show that the major energy consumption in Fijian villages is wood which is used for cooking on open fires. Typical consumption of wood is 1 kg/person/day. (a) Estimate the heat energy required to boil a 2 litre pot full of water. Assuming this to be the cooking requirement of each person, compare this with the heat content of the wood, and thus estimate the thermal efficiency of the open fire. (b) How much timber has to be felled each year to cook for a village of 200 people ? Assuming systematic replanting, what area of crop must the village therefore set aside for fuel use if it is not to make a net deforestation ?arrow_forward
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