Q: The variations of the spectral emissivity of two surfaces are as given
The variations of the spectral emissivity of two surfaces are as given in Fig. P21–40. Determine the average emissivity of each surface at T = 3000 K. Also, determine the average abs...
See AnswerQ: Consider a closed-loop heat exchanger that carries exit water (
Consider a closed-loop heat exchanger that carries exit water (cp = 1 Btu/lbm⋅°F and ρ = 62.4 lbm/ft3) of a condenser side initially at 100°F. The water flows through a 500-ft long stainless steel pip...
See AnswerQ: The emissivity of a surface coated with aluminum oxide can be approximated
The emissivity of a surface coated with aluminum oxide can be approximated to be 0.15 for radiation at wavelengths less than 5 μm and 0.9 for radiation at wavelengths greater than 5 μm. Determine the...
See AnswerQ: Does the reference point selected for the properties of a substance have
Does the reference point selected for the properties of a substance have any effect on thermodynamic analysis? Why?
See AnswerQ: Consider the flow of saturated steam at 270.1 kPa that
Consider the flow of saturated steam at 270.1 kPa that flows through the shell side of a shell-and tube heat exchanger while the water flows through four tubes of diameter 1.25 cm at a rate of 0.25 kg...
See AnswerQ: The variation of the spectral absorptivity of a surface is as given
The variation of the spectral absorptivity of a surface is as given in Fig. P21–42. Determine the average absorptivity and reflectivity of the surface for radiation that originates f...
See AnswerQ: Consider a water-to-water double-pipe heat exchanger
Consider a water-to-water double-pipe heat exchanger whose flow arrangement is not known. The temperature measurements indicate that the cold water enters at 20°C and leaves at 50°C, while the hot wat...
See AnswerQ: The reflectivity of aluminum coated with lead sulfate is 0.35
The reflectivity of aluminum coated with lead sulfate is 0.35 for radiation at wavelengths less than 3 μm and 0.95 for radiation greater than 3 μm. Determine the average reflectivity of this surface f...
See AnswerQ: By taking the limit as ΔT2 → ΔT1, show that when
By taking the limit as ΔT2 → ΔT1, show that when ΔT1 = ΔT2 for a heat exchanger, the ΔTlm relation reduces to ΔTlm = ΔT1 = ΔT2.
See AnswerQ: An opaque horizontal plate is well insulated on the edges and the
An opaque horizontal plate is well insulated on the edges and the lower surface. The irradiation on the plate is 3000 W/m2, of which 500 W/m2 is reflected. The plate has a uniform temperature of 700 K...
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