Engineering :: Renewable Sources of Energy

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91.

For optimum storage of heat with rocks small pebbles should be utilized because

A.	this gives a large surface area to mass ratio	B.	this gives a small surface area to mass ratio
C.	this increases their specific heat	D.	the economical cost of the rocks is decreased

92.

Which of the following statements about using water as a heat-exchange fluid in flat-plate collectors is not true?

A.	It is convenient to obtain and handle	B.	It has a large heat capacity
C.	A large amount of electric power is required to run the water pump	D.	Freeze protection can be obtained by mixing with ethylene glycol

93.

A pure substance at its triple point

A.	exists in gas liquid and solid phases simultaneously	B.	changes directly from solid to vapour
C.	loses phase distinction between liquid and vapour	D.	behaves as an ideal gas

94.

When moist air is cooled by sensible heat removal which of the following is incorrect?

A.	Neither relative humidity nor specific humidity changes	B.	Specific humidity changes but not relative humidity
C.	Both relative humidity and specific humidity change	D.	none of the above

95.

Solar pond is a body of saline water in which the salt concentration

A.	increases from the top surface to the bottom surface	B.	decreases from the top surface to the bottom surface
C.	remains the same in the whole pond	D.	none of the above

96.

Solar pond usually consists of an upper convective layer (UCL) a nonconvective layer (NCL) and a lower lower convective layer (LCL). The solar energy is stored in

A.	UCL	B.	NCL
C.	LCL	D.	UCL and LCL

97.

In solar ponds the upper convective layer

A.	has no useful role in energy collection	B.	is caused by wind action and heat transfer
C.	is considered a homogeneous low salinity layer	D.	all of the above

98.

In solar ponds the transfer of heat and salt is convective in the where UCL NCL and LCL are upper convective layer nonconvective layer and lower convective layer respectively

A.	UCL and LCL	B.	UCL and NCL
C.	NCL and LCL	D.	UCL NCL and LCL

99.

In solar ponds there is a diffusive transport of heat and salt in the

A.	UCL	B.	NCL
C.	LCL	D.	all of the above

100.

The nonconvective layer of solar ponds is an example of

A.	single diffusive system	B.	double diffusive system
C.	triple diffusive system	D.	none of the above