An electric windshield defroster is used to remove 0.25-in of ice from a windshield. The properties of the ice are Tsat = 328F, uif = hif = 144 Btu/lbm, and v = 0.01602 ft3/lbm. Determine the electrical energy required per square foot of windshield surface area to melt this ice and remove it as liquid water at 328F. What is the minimum temperature at which the defroster may be operated? Assume that no heat is transferred from the defroster or ice to the surroundings.

Question No 4: A 4-kW resistance heater in a water heater runs for 2 hours to raise the water temperature to the desired level. Determine the amount of electric energy used in both kWh and kJ.

At atmospheric pressure (100 kPa), the blood of a bilaterally inverted snerg blat has a specific volume of 0.1917 m3/kg and a specific internal energy of 212.18 kJ/kg. What is the specific enthalpy of its blood in kJ/kg

Two electric pumps are being used to pump water to a cistern at the top of a 50 meter hill. A meter is used to measure the electrical energy in kWh consumed by both pumps over a six-hour period. Both pumps consume the same kWh of electrical energy over the pumping period. If we know that pump #1 has an efficiency of 40% and pump #2 has an efficiency of 80%, what can we say about the volume of water moved by each pump? Assume both pumps use the same piping system, so hydraulic frictional losses are the same for both pumps. pump #1 moved twice as much water as pump #2 pump #2 moved twice as much water as pump #1 both pumps moved the same amount of water

Refrigerant 134a is stored inside an uninsulated rigid tank (see figure below) and heated by an electric resistor for 5 minutes. How much energy is lost from the refrigerant through the tank walls during this process? Refer to the table below for properties Resistor R134a Refrigerant Vtank 0.01 m³ -10°C mett F X1-0.8 T₂ = 40°C Battery Current F 5 amp 12-Volt Battery

ANSWERCD

Heat transfer by conductivity: One side of a 3 cm thick copper plate is held at 400°C and the other at 100°C. How much head transferred through the plate?

A torque of 2 N-m is necessary to rotate a paddle wheel at a rate of 20 rad/s.The paddle wheel is located in a rigid vessel containing a gas. What is the net work injoule done on the gas during 10 minutes of operation?

1) A geothermal facility operates at 1/3 of the Carnot efficiency. If the cold reservoirhas a temperature of 70°C, calculate and plot the efficiency of the facility as afunction of the geothermal fluid temperature from 100°C to 300°C. (remember toconvert to Kelvin!)1b) If a minimum efficiency of 5% is needed for this facility to be economicallyviable, what is the required minimum temperature of the geothermal fluid?

Saturated air at 55F dry bulb (db) temperature is heated to 100 F db. The required heating energy, in BTU/lbair,  is most likely:     11 Btu/lbm     15 Btu/lb     9 Btu/lb     5 Btu/lb     20 Btu/lb