A greenhouse system consists of a controller for controlling the system, sensors for detecting the environmental conditions inside the greenhouse and actuators which keep the environment of the greenhouse constant during the summer months. Four thermometers are used to measure the temperature of the greenhouse which automatically turn on the fans and open the windows when the temperature exceeds a certain pre-set value. To satisfy its operational requirements • at least three of the four thermometers are operable, and . at least two out of the five fans are operable, and • at least one of the four windows is operable and . the controller is operable Given that the reliability for the controller is 0.95, the thermometers is 0.92, the fans is 0.9, and the windows is 0.85, calculate the reliability of this system. Please give your answer as a percentage (without the %) to 2 decimal places

A greenhouse system consists of a controller for controlling the system, sensors for detecting the environmental conditions inside the greenhouse and actuators which keep the environment of the greenhouse constant during the summer months. Four thermometers are used to measure the temperature of the greenhouse which automatically turn on the fans and open the windows when the temperature exceeds a certain pre-set value. To satisfy its operational requirements • at least three of the four thermometers are operable, and . at least two out of the five fans are operable, and • at least one of the four windows is operable and . the controller is operable Given that the reliability for the controller is 0.95, the thermometers is 0.92, the fans is 0.9, and the windows is 0.85, calculate the reliability of this system. Please give your answer as a percentage (without the %) to 2 decimal places

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter5: Analysis Of Convection Heat Transfer

Section: Chapter Questions

Problem 5.51P

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3.9 The heat transfer coefficients for the flow of 26.6°C air over a sphere of 1.25 cm in diameter are measured by observing the temperature-time history of a copper ball the same dimension. The temperature of the copper ball was measured by two thermocouples, one located in the center and the other near the surface. The two thermocouples registered, within the accuracy of the recording instruments, the same temperature at any given instant. In one test run, the initial temperature of the ball was 66°C, and the temperature decreased by 7°C in 1.15 min. Calculate the heat transfer coefficient for this case.
Repeat Problem 1.35 but assume that instead of surface temperatures, the given temperatures are those of the air on the left and right sides of the wall and that the convection heat transfer coefficients on the left and right surfaces are 6 and 10W/m2K, respectively.
1.15 A thermocouple (0.8-mm-diameter wire) used to measure the temperature of the quiescent gas in a furnace gives a reading of . It is known, however, that the rate of radiant heat flow per meter length from the hotter furnace walls to the thermocouple wire is 1.1 W/m and the convection heat transfer coefficient between the wire and the gas is K. With this information, estimate the true gas temperature. State your assumptions and indicate the equations used.
Using Table 1.4 as a guide, prepare a similar table showing the orders of magnitude of the thermal resistances of a unit area for convection between a surface and various fluids.
The air-conditioning system in a Chevrolet van for use in desert climates is to be sized. The system is to maintain an interior temperature of 20C when the van travels at 100 km/h through dry air at 30C at night. If the top of the van is idealized as a flat plate 6 m long and 2 m wide and the sides as flat plates 3 m tall and 6 m long, estimate the rate at which heat must be removed from the interior to maintain the specified