50 the emissivity of galvanized steel sheet, a common roofing material, is s = 0.13 at temperatures around 300 k, while its absorptivity for solar irradiation is as = 0.65. would the neighborhood cat be comfortable walking on a roof constructed of the material on a
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a. if a dryer is designed to operate with an electric power consumption of pelec = 500 w and to heat air from an ambient temperature of ti = 20°c to a discharge temperature of to = 45°c, at what volu- metric flow rate 'e should the fan operate? heat loss from the casing to the ambient air and the surround- ings may be neglected. if the duct has a diameter of d = 70 mm, what is the discharge velocity vo of the air? the density and specific heat of the air may
day when gs = 750 w/m2, t00 = 16°c, and h = 7
w/m2 · k? assume the bottom surface of the steel is
insulated.
be approximated as p = 1.10 kg/m3 and cp
j/kg · k, respectively.

-first use of geothermal energy occurred more than 10,000 years ago in north america by american paleo-indians

-the first industrial use of geothermal energy began near pisa, italy in late 18th century

-in 1904, italian scientist piero ginori conti invented the first geothermal electric power plant in which steam was used to generate the power

-with the above experiment, the first geothermal plant in usa started in 1922 with a capacity of 250 kilowatts

-however, in 1946 first ground-source geothermal heat pump installed at commonwealth building in portland, oregon

-during the 1960’s, pacific gas and electric began operation of first large scale geothermal power plant in san francisco, producing 11 megawatts

-in 1973, when oil crisis began many countries began looking for renewable energy sources and by 1980’s geothermal heat pumps (ghp) started gaining popularity in order to reduce heating and cooling costs

-as effect of climate change started showing results, governments of various countries joined hands to fight against it, for which kyoto protocol was signed in japan in 1997, laid out emission targets for rich countries and required that they transfer funds and technology to developing countries, 184 countries have ratified it

hope this