Problem (5): Two concentrating collectors (collector A and collector B) have the same concentration factor of CR = 7 and the optical efficiency of nar = 0.88. The collector temperature for both collectors is 145°C and the ambient air temperature is 27°C. The heat transfer coefficient for collector A is 2.5 W/m2.°C and that for collector B is 3.5 W/m2.°C. The solar irradiation on collector A is 600 W/m?. (a) At what solar irradiation rate does collector B have the same efficiency as collector A? (b) What is the efficiency change of collector A when the solar irradiation increases to 900 W/m2?

Problem (5): Two concentrating collectors (collector A and collector B) have the same concentration factor of CR = 7 and the optical efficiency of nar = 0.88. The collector temperature for both collectors is 145°C and the ambient air temperature is 27°C. The heat transfer coefficient for collector A is 2.5 W/m2.°C and that for collector B is 3.5 W/m2.°C. The solar irradiation on collector A is 600 W/m?. (a) At what solar irradiation rate does collector B have the same efficiency as collector A? (b) What is the efficiency change of collector A when the solar irradiation increases to 900 W/m2?

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

See similar textbooks

Similar questions

Assume a layer of fluid 2 separates fluid 1 from fluid 3. (a) Compare the pressure reflection coefficient for a plane wave traveling in fluid 1 that reflects normally from the layer with that for a plane wave traveling in fluid 3 that reflects normally from the layer. (b) Are the pressure reflection coefficients the same for the two cases? (c) Repeat (a) and (b) for the power reflection and transmission coefficients. (d) What do these results suggest in terms of energy transmission?
1. A glass window allows 95% of radiant energy between 0.32 < 1 < 2.6 microns to pass. Any wavelength outside of this range will not pass through the glass. Compute the energy rate passed through the glass window if the incident energy rate on the glass is 1200 W/m^2. 0.9 0.4 E0-a ot 0.4 0.2 0.1 15,000 AT(Micron-Rankine) S000 10,000 20.000 25,000 30,000 33,000 00 1.0 2.0 3.0 4.0 5.0 6.0 7.0 Amax Ans. 1026 W/m^2
PROBLEM 4: A black thermocouple is inside a chamber with black walls. If the air around the thermocouple is at 20°C, the walls are at 100-C, and the heat transfer coefficient between the thermocouple and the air is 75 W/m²K, what temperature will the thermocouple read?
Determine the heat loss by radiation from an oven wall to the wall of a room to which the oven wall is directly facing. Assume that no heat flows through the adjacent walls, which are coated with a reradiating material. The oven wall is square, 4 ft on one side, and is 2 ft from the room wall and parallel to it. The oven wall is steel sheet and is at 400°F, and the wall is at 80°F and is of asbestos board.
A manufacturing facility located at 32° N latitude has a glazing area of 60 m² facing west that consists of double pane windows made of clear glass (SHGC = 0.766). To reduce the solar heat gain in summer, a reflective film that will reduce the SHGC to 0.35 is considered. The cooling season consists of June, July, August, and September, and the heating season, October through April. The average daily solar heat fluxes incident on the west side at this latitude are 2.35, 3.03, 3.62, 4.00, 4.20, 4.24, 4.16, 3.93, 3.48, 2.94, 2.33, and 2.07 kWh/day · m² for January through December, respectively. Also, the unit costs of electricity and natural gas are $0.09/kWh and $0.45/therm., respectively. If the coefficient of performance of the cooling system is 3.2 and the efficiency of the furnace is 0.90, determine the net annual cost savings due to installing reflective coating on the windows. Also, determine the simple payback period if the installation cost of reflective film is $20/m². Answers:…
Solve fast
A long, horizontal, cylindrical steel reactor, 1 m in diameter, has a surface temperature of 300ºC. The emissivity of the steel is 0.6, and the heat transfer coefficient for natural convection is 5 W m−2 K−1 . Heat is lost by convection to the air at 15ºC, and also by radiation to the surroundings, which can be considered to be a black body at 15ºC. a) Calculate the total heat loss per metre length of the reactor, and the proportions lost by convection and radiation b) The reactor is then insulated with a thin layer of insulation material to reduce the total heat loss to one-tenth of its original value. This causes the surface temperature of the steel to rise to 400ºC. The thermal conductivity of the insulation is 0.01 W m−1 K−1 , and its surface emissivity is 0.2. Show that the resulting surface temperature of the insulation is about 89ºC, and calculate the thickness of insulation required, stating any assumptions made. Specifically need help with part b
A long electrical conductor of 10 mm diameter is concentric with a refrigerated cylindrical tube of 50 mm diameter whose surface has an emissivity of 0.9 and temperature of 27 °C. The electrical conductor has a surface emissivity of 0.6 and dissipates 6.0 W per meter length. Assuming that the space between the two surfaces is empty, calculate the surface temperature of the conductor.
. Calculate the heat transfer rate per m² area by radiation between the surfaces of two long cylinders having radii 100 mm and 50 mm respectively. The smaller cylinder being in the larger cylinder. The axes of the cylinders are parallel to each other and separated by a distance of 20 mm. The surfaces of inner and outer cylinders are maintained at 127°C and 27°C respectively. The emissivity of both the surfaces is 0.5.
An opaque surface which is insulated at the back side has a total, hemispherical absorptivity a=0.8 for solar radiation and a total, hemispherical emissivity of e=0.2. A solar radiation flux of 800 W/m2 is incident on this surface. The surface is exposed to the ambient air at T 300 K and convective heat transfer coefficient is h=15 W/m2 K. Neglect the sky radiation. • Sketch the heat fluxes received and dissipated by this surface • Estimate the equilibrium temperature of the surface (assume the surface temperature is higher than the ambient air temperature). 1.= 300 K, h-15 W/m*K 800 W/m? a-0.8 , e-0.2
Please don't provide handwritten solution
use exact formula. Provide correct answer Fast.