A continuous flow water heater (geyser) has an electrical power rating of $$2kW$$ and efficiency of conversion of electrical power into heat is $$80$$% If water is flowing through device at the constant rate of $$100cc/s$$ and the inlet temperature is $$100C$$,the outlet temperature will be (assume$$ density remains $$constant)

Question

A continuous flow water heater (geyser) has an electrical power rating of  $$2kW$$ and efficiency of conversion of electrical power into heat is $$80$$% If water is flowing through device at the constant rate of $$100cc/s$$ and the inlet temperature is $$100C$$,the outlet temperature will be (assume$$ density remains $$constant)

Infinity Learn · Accepted Answer

Power $$P=dQdt$$⇒$$P=msd$$θ$$dt($$∵$$dQ=msd$$θ$$)$$⇒$$80100$$×$$P=dVdt$$×ρ×s×dθ⇒$$80100$$×$$2000=100$$×$$10$$−$$6$$×$$103$$×$$4200$$×$$($$θ−$$10)$$⇒θ−$$10=3.8$$∴θ$$=13.8$$∘C

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