Answer:
A selective surface with large absorption for solar radiation and high reflectance for thermal infrared radiation was produced by use of surface oxidation of stainless steel. The surfaces were studied for use with concentrated light in a solar power plant at temperatures of 400°C and higher.
In order to investigate the relation between surface treatment and optical properties, stainless steels (AISI 304 and 430) which were submitted to different chemical and mechanical surface treatments, were used. To increase the spectral selectivity, these surfaces were treated in air and in vacuum at different temperatures and times. The optical properties of these films were investigated. Visual and infrared spectral absorptances were measured at room temperature. The thermal hemispherical emittance and absorptance were obtained by a calorimetric method at 200°C. It was noticed that these chemically and mechanically treated stainless steel surfaces have good spectral properties without further oxidations. This is very important for high temperature uses. The best values are found for samples 7 and 8 under vacuum and air. These two samples with mechanically ground surfaces retained their selectivity and specularity after several hours oxidation. One can conclude that the surface ground treatment confers good selectivity on the steel surfaces for use in concentrating solar collectors with a working temperature of 500°C.
Sample surfaces were subjected to long temperature ageing tests in order to gain some idea of the thermal stability of the surfaces. The results promise better-performing surface and the production of durable selective finishes at, possibly, lower cost than competing processes.
Explanation:
Answer:
Explanation:
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In this case, for the inlet stream, from the steam table, the specific enthalpy and entropy are:
Next, for the liquid-vapor mixture at the outlet stream we need to compute its quality by taking into account that since the turbine is adiabatic, the entropy remains the same:
Thus, the liquid and liquid-vapor entropies are included to compute the quality:
Next, we compute the outlet enthalpy by considering the liquid and liquid-vapor enthalpies:
Then, by using the first law of thermodynamics, the maximum specific work is computed via:
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Answer:
The answer which is a calculation can be found as an attached document
Explanation:
Answer: Both Technicians
Explanation:
When testing a spring break it is advisable to Step on and off the brake, with the engine off, the parking brake knob is expected to pop out when air pressure falls between 20-40 psi.
Go under the vehicle and pull the spring brakes.
Turn on the engine back and pump the brake pedal down to the floor. To test the spring breaks
Answer:
The viscosity of the fluid is 6.05 Pa-s
Explanation:
The viscosity obtained from a rotating type viscometer is given by the equation
where
T is the torque applied in the viscometer
't' is the thickness of gap
is the angular speed of rotation
are the outer and the inner raddi respectively
Since it is given that
Applying the values in the above relation we get
