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Sources of Heat

A water coole...

Question

A water cooler of storage capacity $120$ litres can cool water at a constant rate of P watts. In a closed circulation system (as shown schematically in the figure), the water from the cooler is used to cool an external device that generates constantly $3$ kW of heat(thermal load). The temperature of water fed into the device cannot exceed $30$ $^{o} C$ and the entire stored $120$ litres of water is initially cooled to $10$ $^{o} C$ . The entire system is thermally insulated. The minimum value of P(in watts) for which the device can be operated for $3$ hours is? (Specific heat of water is $4.2$ kJ $k g^{- 1} K^{- 1}$ and the density of water is $1000$ kg $m^{- 3}$ ).

1600

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2067

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2533

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3933

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Solution

The correct option is B $2067$
Net power $\times$ time = Heat gained by water

$(3000 - p) 3 \times 60 \times 60 = 120 \times 4200 \times 20$

$P = 2067 W a t t$

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Similar questions

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with in a closed circulation system (as shown schematically in the figure), the water from the cooler is used to cool an external device that generates constantly

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and the entire stored

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The correct option is B 2067Net power × time = Heat gained by water (3000−p)3×60×60=120×4200×20 P=2067Watt

The correct option is B $2067$
Net power $\times$ time = Heat gained by water

$(3000 - p) 3 \times 60 \times 60 = 120 \times 4200 \times 20$

$P = 2067 W a t t$