1 Tractor Test data shows that a tractor has an efficiency o

1) Tractor Test data shows that a tractor has an efficiency of 26 percent when developing 107 hp pulling a load of 6,700 lbs at 5 mph. Determine the rate at which this tractor uses fuel (gal/hr) if a gallon of diesel fuel releases 140,000 BTU of heat when burned.

Diesel Usage Rate = XXX gal/hr

2) A food processing plant is installing a new freezer that has a CoP of 3.8. The freezer is rated at an input power of 86 hp. At what rate (Btu/hr) should this freezer be able to remove heat from the products inside the freezer?

Qout Rate = XXX Btu/hr

Solution

Given that power delivered by tractor = 107 hp at effeciency of 26%

We know 1hp =746 W

Thus effective power delivered = 107*746*0.26

= 20753.72 J/s

= 74713392 Joule/hr

We know 1 BTU = 1055 joules.

Thus rate at which fuel is used = 74713392/(140000*1055)

= 0.5058 gallon/hr