Refrigerant 134a enters a compressor operating at steady state as saturated vapor at 0.12 MPa and exits at 1.2 MPa and $70^{\circ}C$ at a mass flow rate of 0.108 kg/s. As the refrigerant passes through the compressor, heat transfer to the surroundings occurs at a rate of 0.32 kJ/s. Determine at steady state the power input to the compressor, in kW.

The compressor in a refrigerator compresses saturated R-134a vapor to 0$^\circ{}$F to 200 psia. Calculate the work required by this compressor, in Btu/lbm, when the compression process is isentropic.

Refrigerant-134a enters a compressor as a saturated vapor at 160 kPa at a rate of $0.03 \mathrm{m}^{3} / \mathrm{s}$ and leaves at 800 kPa. The power input to the compressor is 10 kW. If the surroundings at $20^{\circ} \mathrm{C}$ experience an entropy increase of 0.008 kW/K, determine

(a) the rate of heat loss from the compressor,

(b) the exit temperature of the refrigerant, and

(c) the rate of entropy generation.

A reversible steady-state device receives a flow of 1 kg/s air at 400 K, 450 kPa and the air leaves at 600 K, 100 kPa. Heat transfer of 900 kW is added from a 1000K reservoir, 50 kW is rejected at 350 K, and some heat transfer takes place at 500 K. Find the heat transferred at 500 K and the rate of work produced.

Refrigerant-134a enters the compressor of a refrigeration system as saturated vapor at 0.14 MPa and leaves as superheated vapor at 0.8 MPa and 60$^\circ{}$C at a rate of 0.06 kg/s. Determine the rates of energy transfers by mass into and out of the compressor. Assume the kinetic and potential energies to be negligible.

Refrigerant- $134 \mathrm{a}$ enters an adiabatic compressor as saturated vapor at $160 \mathrm{~kPa}$ at a rate of $2 \mathrm{~m}^{3} / \mathrm{min}$ and is compressed to a pressure of $900 \mathrm{~kPa}$. Find the minimum power that must be supplied to the compressor.

In which one or more of the following situations is the principle of conservation of mechanical energy obeyed? (a) An object moves uphill with an increasing speed. (b) An object moves uphill with a decreasing speed. (c) An object moves uphill with a constant speed. (d) An object moves downhill with an increasing speed. (e) An object moves downhill with a decreasing speed. (f) An object moves downhill with a constant speed.

A gas enters a compressor operating at steady state and is compressed isentropically. Does the specific enthalpy increase or decrease as the gas passes from the inlet to the exit?

Refrigerant 134a enters an insulated compressor operating at steady state as saturated vapor at $-20^{\circ}C$ with a mass flow rate of 1.2 kg/s. Refrigerant exits at 7 bar, $70^{\circ}C$. Changes in kinetic and potential energy from inlet to exit can be ignored. Determine (a) the volumetric flow rates at the inlet and exit, each in $m^3/s$, and (b) the power input to the compressor, in kW.

Steam enters the first-stage turbine shown in figure at 40 bar and $500^{\circ} \mathrm{C}$ with a volumetric flow rate of $90 \mathrm{~m}^3 / \mathrm{min}$. Steam exits the turbine at 20 bar and $400^{\circ} \mathrm{C}$. The steam is then reheated at constant pressure to $500^{\circ} \mathrm{C}$ before entering the second-stage turbine. Steam leaves the second stage as saturated vapor at $0.6$ bar. For operation at steady state, and ignoring stray heat transfer and kinetic and potential energy effects, determine the (a) mass flow rate of the steam, in $\mathrm{kg} / \mathrm{h}$. (b) total power produced by the two stages of the turbine, in $\mathrm{kW}$. (c) rate of heat transfer to the steam flowing through the reheater, in $\mathrm{kW}$.

Saturated water vapor at $300^\circ F$ enters a compressor operating at steady state with a mass flow rate of 5 lb/s and is compressed adiabatically to $800 lbf/in.^2$ If the power input is 2150 hp, determine for the compressor (a) the isentropic compressor efficiency and (b) the rate of entropy production, in $hp/^\circ R.$ Ignore kinetic and potential energy effects.

Steam enters a turbine operating at steady state with a mass flow of 10 kg/min, a specific enthalpy of 3100 kJ/kg, and a velocity of 30 m/s. At the exit, the specific enthalpy is 2300 kJ/kg and the velocity is 45 m/s. The elevation of the inlet is 3 m higher than at the exit. Heat transfer from the turbine to its surroundings occurs at a rate of 1.1 kJ per kg of steam flowing. Let $g=9.81 m/s^2$. Determine the power developed by the turbine, in kW.

Determine whether the statement is true or false. Explain your answer. In our model for free-fall motion retarded by air resistance, the terminal velocity is proportional to the weight of the falling object.

Some bottled water is now advertised as containing extra quantities of “Vitamin O,” which is a marketing gimmick for selling oxygen, O2. Might this bottle water actually contain extra quantities of oxygen, O2? How much more O2 than one might find in regular bottled water? How might the amount of oxygen we absorb through our lungs compare to the amount we might absorb through our stomach-after burping?