A hermetically sealed room 4 m x 4 m x 4 m has an internal sensible heat gain of 3 kW. The overall heat – transfer coefficient of its wall, floor and ceiling is 1.1 W/m2K. The outside temperature is constant at 37 °C. Calculate the steady – state temperature of the room. What will be the temperature maintained inside the room if the ventilation air supplied is equivalent to 10 air changes per hour?

A hermetically sealed room 4 m x 4 m x 4 m has an internal sensible heat gain of 3 kW. The overall heat – transfer coefficient of its wall, floor and ceiling is 1.1 W/m2K. The outside temperature is constant at 37 °C. Calculate the steady – state temperature of the room. What will be the temperature maintained inside the room if the ventilation air supplied is equivalent to 10 air changes per hour?

University Physics Volume 2

18th Edition

ISBN:9781938168161

Author:OpenStax

Publisher:OpenStax

Chapter3: The First Law Of Thermodynamics

Section: Chapter Questions

Problem 66P: One of a dilute diatomic gas occupying a volume of 10.00 L expands against a constant pressure of...

See similar textbooks

Similar questions

The thermal conductivities of human tissues vary greatly. Fat and skin have conductivities of about 0.20 W/m K and 0.020 W/m K, respectively, while other tissues inside the body have conductivities of about 0.50 W/m K. Assume that between the core region of the body and the skin sin face lies a skin layer of 1.0 mm, fat layer of 0.50 cm, and 3.2 cm of other tissues. (a) Find the R-factor for each of these layers, and the equivalent R-factor for all layers taken together, retaining two digits. (b) Find the rate of energy loss when the core temperature is 37C and the exterior temperature is 0C. Assume that both a protective layer of clothing and an insulating layer of unmoving air a absent, and a body area of 2.0 m2.
One of a dilute diatomic gas occupying a volume of 10.00 L expands against a constant pressure of 2.000 atm when it is slowly heated. If the temperature of the gas rises by 10.00 K and 400.0 J of heat are added in the process, what is its final volume?
In the heating seasons the heat loss from a building (and thus the heating cost) is strongly dependent on the difference between the indoor and outdoor temperature. If the average outdoor temperature in a particular city during the heating season is 45 F (7 C), what is the effect on heating cost percentage-wise if the thermostat setting is fixed at 74 F (23.3 F) instead of 68 F (20 C)?
For a temperature difference ΔT = 20C, one slab of material conducts 10W/m². What is the rate of heat flow per m² of surface area when the slabs are placed side by side with ΔTtot = 20C?
Suppose you want to raise the temperature of a mass m of ice from T0 < 0 °C to T > 100 °C. In this problem, represent the heat of fusion as Lf, the heat of vaporization as Lv, and the temperatures at which the phase changes occur as Tf and Tv. How much heat must be transferred for this to happen, including the energy needed for phase changes? Your answer should be in terms of the variables in the introduction and the specific heats of ice (ci), water (cw), and steam (cs). The talent heats are Lf= 334kJ/kg and Lv=2256kJ/kg?
Compute the heat transfer through the air condition if the outside temperature is outside temperature, To = 5 degrees Celsius, inside temperature = 20 degrees Celsius, in a room with length 5 m, width of 6 m and height of 4 m. A typical volume flow for ventilation is 20 liters/second or 0.02 cubic meter/s, how much time will it take to replace all air within this room? Then, compute total thermal power flux out of the room through the ventilation? Given, Cp = 1005 J/khK, and roho = 1.2 kg/cubic.
ANSWER THE FF and SHOW COMPLETE SOLN: a.) An aluminum sheet of thickness 8.3 cm and area 13 m^2 is welded on top of a brass sheet of the same thickness and area. The thermal conductivities of aluminum and brass are 205 W/m·K and 109 W/m·K, respectively. The aluminum end is kept at 20 °C while the brass end is kept at 30 °C. At the moment when the interface temperature is 24 °C, what is the heat current through the brass sheet? (answer for this is: 102 kW) b.) A 10.0-cm long steel rod is welded end to end to a 20.0-cm long copper rod of the same cross-sectionalarea. The thermal conductivities of steel and copper are 50.2 W/m·K and 385 W/m·K, respectively. The steel endis kept at 100 °C while the copper end is kept at 0 °C. What is the steady-state temperature at the interfaceconnecting the two rods? (answer for this is 20.7 °C)
To illustrate the effect of ice on the aluminum cooling plate, consider the drawing shown here and the data that it contains. Ignore any limitaions due to significant figures. How much heat per second per square meter is conducted through the ice-aluminum combination and through the aluminum by itself?
An aluminum wire is wrapped in rubber insulation. Both are subject to thermal expansion, with the following coefficients of linear expansion: alphaa=24· 10−6 1/C and alphar=8· 10−5 1/C . If the wire and insulation are the same length of 1.85m at a temperature of20.00°C, what is the difference in length (in MILLIMETERS) between the copper wire and the rubber insulation when heated up to a temperature of 189.00°C? Express a magnitude only (no negatives!). ______mm (MILLIMETERS!)
A 2-m * 1.5-m section of wall of an industrial furnaceburning natural gas is not insulated, and the temperatureat the outer surface of this section is measured to be 80°C.The temperature of the furnace room is 30°C, and the combinedconvection and radiation heat transfer coefficient at thesurface of the outer furnace is 10 W/m2·K. It is proposed toinsulate this section of the furnace wall with glass wool insulation(k = 0.038 W/m·K) in order to reduce the heat lossby 90 percent. Assuming the outer surface temperature ofthe metal section still remains at about 110°C, determine thethickness of the insulation that needs to be used.The furnace operates continuously and has an efficiency of78 percent. The price of the natural gas is $1.10/therm (1 therm =105,500 kJ of energy content). If the installation of the insulationwill cost $250 for materials and labor, determine how long it willtake for the insulation to pay for itself from the energy it saves.
Judging from its unit W/m·K, can we define thermal conductivity of a material as the rate of heat transfer through the material per unit thickness per unit temperature difference? Explain.
A window measures 1.5 m by 0.2 m and the single pane of glass is 0.3 cm thick. The outside temperature is 39 deg C and the inside temperature is 20 deg C, Find the rate of heat flow (that is, find Q/t) as heat travels through the window, and give as a positive answer. The glass has a thermal conductivity (k) of 0.8 W/(m degC) .