The maximum flow rate of a standard shower head isabout 3.5 gpm (13.3 L/min) and can be reduced to 2.75 gpm(10.5 L/min) by switching to a low-flow shower head that isequipped with flow controllers. Consider a family of four,with each person taking a 6-minute shower every morning. City water at 15°C is heated to 55°C in an oil water heater whose efficiency is 65 percent and then tempered to 42°C by cold water at the T-elbow of the shower before being routed to the shower head. The price of heating oil is $2.80/gal and its heating value is 146,300 kJ/gal. Assuming a constant specific heat of 4.18 kJ/kg∙°C for water, determine the amount of oil and money saved per year by replacing the standard shower heads by the low-flow ones.

The maximum flow rate of a standard shower head is
about 3.5 gpm (13.3 L/min) and can be reduced to 2.75 gpm
(10.5 L/min) by switching to a low-flow shower head that is
equipped with flow controllers. Consider a family of four,
with each person taking a 6-minute shower every morning. City water at 15°C is heated to 55°C in an oil water heater
whose efficiency is 65 percent and then tempered to 42°C by
cold water at the T-elbow of the shower before being routed
to the shower head. The price of heating oil is $2.80/gal and
its heating value is 146,300 kJ/gal. Assuming a constant specific
heat of 4.18 kJ/kg∙°C for water, determine the amount
of oil and money saved per year by replacing the standard
shower heads by the low-flow ones.