Thermal Storage Solar heating of a house is much more efficient if there is a way...
Thermal Storage Solar heating of a house is much more efficient if there is a way to store the thermal energy collected during the day to warm the house at night. Suppose one solar-heated home utilizes a concrete slab of area 11 m2 and 26 cm thick.
If the density of concrete is 2400 kg/m3, what is the mass of the slab?
The slab is exposed to sunlight and absorbs energy at a rate of 1.2 ×107J/h for 10 h. If it begins the day at 25 ∘C and has a specific heat of 750 J/(kg⋅K), what is its temperature at sunset?
Model the concrete slab as being surrounded on both sides (contact area 22 m2) with a 1.7-m-thick layer of air in contact with a surface that is 5.0 ∘C cooler than the concrete. At sunset, what is the rate at which the concrete loses thermal energy by conduction through the air layer?
Model the concrete slab as having a surface area of 24 m2 and surrounded by an environment 5.0 ∘C cooler than the concrete. If its emissivity is 0.91, what is the rate at which the concrete loses thermal energy by radiation at sunset?
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Thermal Storage Solar heating of a house is much more efficient
if there is a way...
P2 (50 pts.) Assume the roof of a room in a typical house is 12 cm...
P2 (50 pts.) Assume the roof of a room in a typical house is 12 cm thick concrete slab with a thermal conductivity k = 1.50 W/m•°C. The roof of the room is 4 m wide and 4 m long. Assume convection heat transfer coefficients on the inner and outer surfaces of the roof are hi=6 and ho=10 W/m2°C, respectively. At noon, when the sun is "hotter" the solar irradiation is estimated to be color = 750 W/m- and the...
Heat Loss and Heating Costs of a House Part A A house has well-insulated walls 17.1...
Heat Loss and Heating Costs of a House Part A A house has well-insulated walls 17.1 cm thick (assume conductivity of air) and area 411 m2, a roof of wood б.бб cm thick and area 279 m2, and uncovered windows 0.626 cm thick and total area 33.4 m2. Assuming that the heat loss is only by conduction, calculate the rate at which heat must be supplied to this house to maintain its temperature at 21.4°C if the outside temperature is...
Ch 17 HW Problem 17.104 Constants Animals in cold climates often depend on two layers of...
Ch 17 HW Problem 17.104 Constants Animals in cold climates often depend on two layers of insulation a layer of body fat jof thermal conductivity 0 200 W/(m K)I surrounded by a layer of air trapped inside fur or down We can model a black bear (Ursus americanus) as a sphere 1.40 m in diameter having a layer of fat 4 10 cm thick (Actually the thickness varies with the season, but we are interested in hibernation, when the fat...
Calculate the rate of energy loss due to thermal radiation from an unclothed person if the average skin temperature is...
Calculate the rate of energy loss due to thermal radiation from an unclothed person if the average skin temperature is 37 °C and the room temperature is 20 °C. You may sume a total surface area of 1.5 m and a skin emissivity value of 0.9. How much energy (from food) must be consumed per day to compensate for this loss? If the person is surrounded by a layer of insulation of thickness 1.0 cm with a thermal conductivity of...
Both please 13.3 Estimate the amount of solar heating that is lost as a result of using one or two tempered 1/8 in thick glass plates covering a flat-plate absorber. The transmission coefficient for r...
Both please
13.3 Estimate the amount of solar heating that is lost as a result of using one or two tempered 1/8 in thick glass plates covering a flat-plate absorber. The transmission coefficient for radiation is 2% for wavelengths greater than 3 m and 80% for wavelengths ranging from 0.2 to 3 um. 13.4 The amount of solar energy captured in a given application is expressed in terms of how much thermal energy is delivered relative to the total demand...
10. (10pts) The surface area of an adult human being is 1,8 m2. Suppose a person with a skin tem ...
10. (10pts) The surface area of an adult human being is 1,8 m2. Suppose a person with a skin tem omperature of 34°C is standing with bare skin in a room where the air is 22°C but the walls are 21°C. (ơ 5.67" 104 J / (sm"к"). There is a "dead ai lay ran around you next to your skin that acts as insulation. This dead-air layer is 5.0 mm thick. a) Draw b) What is the person's rate of...
Homework 7 heat transfer 2018-20 1) A horizontal tube of 12.5-mm dimeter with an outer srface temperature of 240°C is placed in a room with an air temperature of 20°C. Estimate the heat transfer rate...
Homework 7 heat transfer 2018-20 1) A horizontal tube of 12.5-mm dimeter with an outer srface temperature of 240°C is placed in a room with an air temperature of 20°C. Estimate the heat transfer rate per unit length of the tube due to free convection. 2) Air at -10°C flows at 10 m/s over the roof plate of two 5m length rooms whose air is at Too-200C. The roof plate is 0.20-m thick concrete (k = 0.6 w/ m. K)....
please show work = The use of rock pile thermal energy storage systems has been considered...
please show work
= The use of rock pile thermal energy storage systems has been considered for solar energy and industrial process heat applications. A particular system involves a cylindrical container, 2 m long by 1 m in diameter, in which nearly spherical rocks of 0.03-m diameter are packed. The bed has a void space of 0.42, and the density and specific heat of the rock are p = 2300 kg/m and cp = 879 J/kg-K, respectively. Consider conditions for...
(33%) Problem 3: Warm blooded animals are home otherm that is, they maintain an approximately constant...
(33%) Problem 3: Warm blooded animals are home otherm that is, they maintain an approximately constant body temperature. (For humans it's about 37°C.) When they are in an environment that is below their optimum temperature, they use energy derived from chemical reactions within their bodies to warm them up One of the ways that animals lose energy to their environment is through radiation. Every object emits electromagnetic radiation that depends on its temperature. For very hot objects like the sun,...
(33%) Problem 3: Warm blooded animals are homeothermic that is, they maintain an approximately constant body...
(33%) Problem 3: Warm blooded animals are homeothermic that is, they maintain an approximately constant body temperature. (For humans it's about 37°C.) When they are in an environment that is below their optimum temperature, they use energy derived from chemical reactions within their bodies to warm them up. One of the ways that animals lose energy to their environment is through radiation. Every object emits electromagnetic radiation that depends on its temperature. For very hot objects like the sun, that...
P2 (50 pts.) Assume the roof of a room in a typical house is 12 cm thick concrete slab with a thermal conductivity k = 1.50 W/m•°C. The roof of the room is 4 m wide and 4 m long. Assume convection heat transfer coefficients on the inner and outer surfaces of the roof are hi=6 and ho=10 W/m2°C, respectively. At noon, when the sun is "hotter" the solar irradiation is estimated to be color = 750 W/m- and the...
Heat Loss and Heating Costs of a House Part A A house has well-insulated walls 17.1 cm thick (assume conductivity of air) and area 411 m2, a roof of wood б.бб cm thick and area 279 m2, and uncovered windows 0.626 cm thick and total area 33.4 m2. Assuming that the heat loss is only by conduction, calculate the rate at which heat must be supplied to this house to maintain its temperature at 21.4°C if the outside temperature is...
Ch 17 HW Problem 17.104 Constants Animals in cold climates often depend on two layers of insulation a layer of body fat jof thermal conductivity 0 200 W/(m K)I surrounded by a layer of air trapped inside fur or down We can model a black bear (Ursus americanus) as a sphere 1.40 m in diameter having a layer of fat 4 10 cm thick (Actually the thickness varies with the season, but we are interested in hibernation, when the fat...
Calculate the rate of energy loss due to thermal radiation from an unclothed person if the average skin temperature is 37 °C and the room temperature is 20 °C. You may sume a total surface area of 1.5 m and a skin emissivity value of 0.9. How much energy (from food) must be consumed per day to compensate for this loss? If the person is surrounded by a layer of insulation of thickness 1.0 cm with a thermal conductivity of...
Both please
13.3 Estimate the amount of solar heating that is lost as a result of using one or two tempered 1/8 in thick glass plates covering a flat-plate absorber. The transmission coefficient for radiation is 2% for wavelengths greater than 3 m and 80% for wavelengths ranging from 0.2 to 3 um. 13.4 The amount of solar energy captured in a given application is expressed in terms of how much thermal energy is delivered relative to the total demand...
10. (10pts) The surface area of an adult human being is 1,8 m2. Suppose a person with a skin tem omperature of 34°C is standing with bare skin in a room where the air is 22°C but the walls are 21°C. (ơ 5.67" 104 J / (sm"к"). There is a "dead ai lay ran around you next to your skin that acts as insulation. This dead-air layer is 5.0 mm thick. a) Draw b) What is the person's rate of...
Homework 7 heat transfer 2018-20 1) A horizontal tube of 12.5-mm dimeter with an outer srface temperature of 240°C is placed in a room with an air temperature of 20°C. Estimate the heat transfer rate per unit length of the tube due to free convection. 2) Air at -10°C flows at 10 m/s over the roof plate of two 5m length rooms whose air is at Too-200C. The roof plate is 0.20-m thick concrete (k = 0.6 w/ m. K)....
please show work
= The use of rock pile thermal energy storage systems has been considered for solar energy and industrial process heat applications. A particular system involves a cylindrical container, 2 m long by 1 m in diameter, in which nearly spherical rocks of 0.03-m diameter are packed. The bed has a void space of 0.42, and the density and specific heat of the rock are p = 2300 kg/m and cp = 879 J/kg-K, respectively. Consider conditions for...
(33%) Problem 3: Warm blooded animals are home otherm that is, they maintain an approximately constant body temperature. (For humans it's about 37°C.) When they are in an environment that is below their optimum temperature, they use energy derived from chemical reactions within their bodies to warm them up One of the ways that animals lose energy to their environment is through radiation. Every object emits electromagnetic radiation that depends on its temperature. For very hot objects like the sun,...
(33%) Problem 3: Warm blooded animals are homeothermic that is, they maintain an approximately constant body temperature. (For humans it's about 37°C.) When they are in an environment that is below their optimum temperature, they use energy derived from chemical reactions within their bodies to warm them up. One of the ways that animals lose energy to their environment is through radiation. Every object emits electromagnetic radiation that depends on its temperature. For very hot objects like the sun, that...
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