The diagram shows a simplified version of how an air conditioner

works. A liquid refrigerant $($represented by stream $1$ in the figure$)$

passes through an expansion valve, where it flashes to a lower

pressure and partially evaporates. This liquid$-$vapor mixture

$($represented by stream $2)$ passes through an evaporator coil that cools

indoor air. Heat absorbed from the indoor air causes the refrigerant to

completely vaporize. This vapor stream $($represented by stream $3)$

goes to an adiabatic compressor, where it is pressurized. During the

pressurization process, the temperature is simultaneously raised. This

superheated vapor $($represented by stream $4)$ passes through a

condenser, where the stream is cooled to condensation by outside air.

After condensation, the refrigerant is at the same conditions as it was

in the start of the cycle.

Consider the refrigeration cycle applied to the refrigerant

chlorodifluoromethane $,$ referred to in industry as R$-22).$

$R-22$ is circulated through the air conditioner at a rate of

$79\mathrm{.}00l\frac{b_m}{m}in.$ The streams are at the conditions listed.

Stream $1$: liquid, $95F,197,$hat$(H{)}_{\text{l}\text{i}\text{q}}=104\mathrm{.}8Bt\frac{u}{l}{b}_m$

Stream $2$: liquid and vapor, $37F,79\mathrm{.}5,$hat$(H{)}_{\text{l}\text{i}\text{q}}=87\mathrm{.}75Bt\frac{u}{l}{b}_m,$hat$(H{)}_{\text{v}\text{a}\text{p}}=175\mathrm{.}1Bt\frac{u}{l}{b}_m$

Stream $3$: vapor, $37F,79\mathrm{.}5,$hat$(H{)}_{\text{v}\text{a}\text{p}}=175\mathrm{.}1Bt\frac{u}{l}{b}_m$

Stream $4$: vapor, $122F,197,$hat$(H{)}_{\text{v}\text{a}\text{p}}$~~$185\mathrm{.}0Bt\frac{u}{l}{b}_m$

If the expansion valve operates adiabatically and $E_k^{}$ is

negligible, perform an energy balance around the valve to

determine the fraction of the refrigerant that evaporates at the

fraction of refrigerant evaporated:

expansion valve.

What is the rate of heat transfer to evaporating refrigerant in

the evaporator coil?

$Q_B^{}=$

If the refrigerant loses $6340Bt\frac{u}{m}in$ in heat through the

condenser, calculate the horsepower the compressor must

input to the refrigerant.

$W_s^{}=$