Steam enters a counterflow heat exchanger operating at steady state at 0.07 MPa with a specific enthalpy of 2431.6 kJ/kg and exits at the same pressure as saturated liquid. The steam mass flow rate is 1.5 kg/min. A separate stream of air with a mass flow rate of 100 kg/min enters at $30^{\circ}C$ and exits at $60^{\circ}C.$. The ideal gas model with $c_{p}= 1.005 \: kJ/kg \cdot K$ can be assumed for air. Kinetic and potential energy effects are negligible. Determine (a) the quality of the entering steam and (b) the rate of heat transfer between the heat exchanger and its surroundings, in kW.

When 2.4 g of Co(NO3)2 is dissolved in 0.350 L of 0.22 M KOH, what are [Co2+], [Co(OH)42-], and [OH-] [Kf of Co(OH)42- = 5 $\times$ 109]?

Air ($c_{p}$ = 1.005 kJ/kgK) is to be preheated by hot exhaust gases in a cross-flow heat exchanger before it enters the furnace. Air enters the heat exhanger at 95 kPa and 20$^\circ{}$C at a rate of 0.6 m^3/s. The combustion gases ($c_{p}$ = 1.10 kJ/kgK) enter at 160$^\circ{}$C at a rate of 0.95 kg/s and leave at 95$^\circ{}$C. Determine the rate of heat transfer to the air and its outlet temperature.

Saturated liquid water is heated in a steady-flow steam boiler at a constant pressure of 2 MPa at a rate of 4 kg/s to an outlet temperature of 250$^\circ{}$C. Determine the rate of heat transfer in the boiler.

Liquid water enters a heat exchanger operating at steady state at $T_{1}=60^{\circ} \mathrm{F}, p_{1}=1$ atm and exits at $T_2 = 160^\circ F$ with a negligible change in pressure. In a separate stream, steam enters at $T_{3}=20 \mathrm{lbf} / \mathrm{in}^{2}, x_{3}= 92$ and exits at $T_{4}=140^{\circ} \mathrm{F}, p_{4}=18 \mathrm{lbf} / \mathrm{in}^{2}.$ Stray heat transfer and the effects of motion and gravity are negligible. Let $T_{0}=60^{\circ} \mathrm{F}, p_{0}= 1 atm.$ Determine (a) the ratio of the mass flow rates of the two streams and (b) the rate of exergy destruction, in Btu per lb of steam entering the heat exchanger.

What direction is the net energy transfer by work for a power cycle: in or out? The net energy transfer by heat?

Steam enters a heat exchanger operating at steady state at 250 kPa and a quality of 90% and exits as saturated liquid at the same pressure. A separate stream of oil with a mass flow rate of 29 kg/s enters at $20^{\circ}C$ and exits at $100^{\circ}C$ with no significant change in pressure. The specific heat of the oil is $c = 2.0 \: kJ/kg \cdot K.$ Kinetic and potential energy effects are negligible. If heat transfer from the heat exchanger to its surroundings is 10% of the energy required to increase the temperature of the oil, determine the steam mass flow rate, in kg/s.

Determine the gravitational potential energy, in kJ, of $2 m^3$ of liquid water at an elevation of 30 m above the surface of Earth. The acceleration of gravity is constant at $9.7 m/s^2$ and the density of the water is uniform at $1000 kg/m^3$. Determine the change in gravitational potential energy as the elevation decreases by 15 m.

Air enters a compressor operating at steady state at 1.05 bar, 300 K, with a volumetric flow rate of $12 \:m^3/min$ and exits at 12 bar, 400 K. Heat transfer occurs at a rate of 2 kW from the compressor to its surroundings. Assuming the ideal gas model for air and neglecting kinetic and potential energy effects, determine the power input, in kW.

The change in total energy of a closed system other than changes in kinetic and gravitational potential energy are accounted for by the change in ________.

Refrigerant 134a enters an air conditioner compressor at 4 bar, $20^{\circ}C$, and is compressed at steady state to 12 bar, $80^{\circ}C$. The volumetric flow rate of the refrigerant entering is $4 \: m^3/min.$ The work input to the compressor is 60 kJ per kg of refrigerant flowing. Neglecting kinetic and potential energy effects, determine the heat transfer rate, in kW.

Refrigerant 134a enters a well-insulated nozzle at 14 bar, $60^\circ C,$ with a velocity of 37 m/s and exits at 1.2 bar with a velocity of 460 m/s. For steady-state operation, and neglecting potential energy effects, determine the exit velocity, m/s.

A well-insulated turbine operating at steady state develops 28.75 MW of power for a steam flow rate of 50 kg/s. The steam enters at 25 bar with a velocity of 61 m/s and exits as saturated vapor at 0.06 bar with a velocity of 130 m/s. Neglecting potential energy effects, determine the inlet temperature, in $^{\circ}C$.

What are the three modes of energy storage for individual atoms and molecules making up the matter within a system?