Photovoltaic electric production A. is carried in water or other liquids to places where it is needed. B. is a direct conversion of solar energy to electricity, such as in solar-powered calculators. C. is heat collected directly from sunshine. D. is a result of the heat absorbed by collectors, such as those on rooftops.

Explain the difference laminar and turbulent flow. explain it with the shear stress and the velocity profiles.

Aquick transition of the operating speed of a shaft from its critical speed will whirl amplitude. (a) increase (b) limit (c) not affect (d) zero

Athin walled concentric tube exchanger is used to cool engine oil from 160°c to 60°c with water that is available at 25°c acting as a coolant. the oil and water flow rates are each at 2 kg/s, and the diameter of the inner tube is 0.5 m and the corresponding value of the overall heat transfer coefficient is 250 w/m2. oc. how long must the heat exchanger be to accomplish the desired cooling? cpwater=4.187 kj/kg-candcpengine el=2.035 kj/kg·°c, oil . 120]