Problem: The condenser in an air conditioning system is a heat exchanger in which cool air...
Problem:
The condenser in an air conditioning system is a heat exchanger in which cool air absorbs latent energy from the refrigerant, condensing the refrigerant from vapor to liquid. Refrigerant R-134 enters the condenser at 1 MPa and 90°C. It leaves the condenser at 1 MPa and 30°C. Cool air enters the condenser at 100 kPa and 27°C at a volume flow rate of 10 m3/s, and it leaves at 95 kPa and 60°C. Assume the specific heat of the air is constant at cp = 1.005 kJ/kg·K. Determine the mass flow rate of the refrigerant, in kg/s. Assume all systems are steady-flow and steady-state (dEcv/dt = dmcv/dt = 0), and all gases except for steam and refrigerant vapor are ideal.
Please use the refrigerant 134a tables online.
Also, please do the following in the work:
-Sketch a FBD
-Include units or state units in each part (writing the variables with the units then just plugging the numbers in with units is fine too)
-State the Original formula used to derive each problem
Thank you!
Homework Answers
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Problem:
The condenser in an air conditioning system is a heat exchanger
in which cool air...
Condenser Compressor An ideal vapor-compression refrigeration cycle is modified to include a counter-flow heat exchanger as...
Condenser Compressor An ideal vapor-compression refrigeration cycle is modified to include a counter-flow heat exchanger as shown. Refrigerant 134a leaves the evaporator as saturated vapor at 0.10 MPa and is heated at constant pressure to 20°C before entering the compressor. Following isentropic compression to 1.4 MPa, the refrigerant passes through the condenser and exits at 45°C and 1.4 MPa. The liquid then passes through the heat exchanger and enters the expansion valve at 1.4 MPa. The mass flow rate of...
1. (100 points) A counterflow heat exchanger operates at steady state to transfer heat between air...
1. (100 points) A counterflow heat exchanger operates at steady state to transfer heat between air and refrigerant 134a. The air enters at 22°C and 0.1 MPa, then exits at 7°C. The R-134a enters at 0°C at a rate of 30 kg/h by mass, and is a saturated vapor upon exit. Both streams experience no notable change in pressure. (a) Determine the heat transfer rate and associated rate of exergy transfer for the R-134a stream in kJ/h. (b) Evaluate the...
In a produce chilling system, air is cooled by being passed over a heat exchanger coil througlh w...
Please use EES only.
In a produce chilling system, air is cooled by being passed over a heat exchanger coil througlh which R-134a flows steadily at a rate of 15 lbm/min. Prior to entering the heat exchanger coil, the refrigerant passes through a throttling valve as shown in the figure below. The R-134a enters the valve as a saturated liquid at high pressure (which will be varied) and leaves at 35 psia. The refrigerant leaves the heat exchanger coil as...
A two-pass shell and tube heat exchanger has an overall conductance l of 450 W/m20 C...
A two-pass shell and tube heat exchanger has an overall conductance l of 450 W/m20 C when used as a condenser for a large air conditioning system. Refrigerant R-134a enters the condenser at 20 kg/ s as a saturated vapor at 70 C and leaves as a saturated liquid. If cooling water enters at a rate of 60 L/s, 10 ° C, determine the outlet temperature of the cooling water and the effective area of the condenser
A car air conditioning system takes air at 35 °C from the surrounding atmosphere and cools...
A car air conditioning system takes air at 35 °C from the surrounding atmosphere and cools it down to 15 °C in a heat exchanger from which heat is removed by an ideal refrigeration cycle using refrigerant 134a. The condenser pressure is 1.2 MPa and the evaporator pressure is 0.2 MPa. If the car engine can supply 2 kW of power to run the air conditioner what is the maximum mass flow rate of cold air that can be supplied
Problem I: Not applicable for 2017 Problem II: In an R-134a vapor-compression home heat pump, R-134A...
Problem I: Not applicable for 2017 Problem II: In an R-134a vapor-compression home heat pump, R-134A enters the compressor (75% isentropic efficiency) as a saturated vapor at 200 kPa and leaves at 800 kPa. The refrigerant goes through a constant pressure condenser and leaves as a saturated liquid. The refrigerant then goes through an adiabatic expansion valve enters the evaporator as a liquid-vapor mixture. The mass flow rate of refrigerant is 0.1 kg/s. and Cod A. Write the equation for...
5. Refrigerant-134a at 700kPa, 70°C, and 8 kg/min is cooled by air in a condenser until...
5. Refrigerant-134a at 700kPa, 70°C, and 8 kg/min is cooled by air in a condenser until it exits as a saturated liquid at the same pressure. The cooling air enters the condenser at 1MPa and 10°C and leaves at 17°C at the same pressure. Determine: a) Considering only the Refrigerant as a system, the heat transfer rate of a refrigerant from the condenser in (kl/min). R-134a Tables are attached! b) The mass flow rate of the air required for cooling...
3. An air-conditioning system is shown in Fig.3, in which air flows over tubes carrying Refrigerant...
3. An air-conditioning system is shown in Fig.3, in which air flows over tubes carrying Refrigerant 134a. Air enters with a volumetric flow rate of 50 m3/min at 32°C, 1 bar, and exits at 22°C, 0.95 bar. Refrigerant enters the tubes at 5 bar with a quality of 20% and exits at 5 bar, 20°C. Ignoring heat transfer at the outer surface of the air conditioner, and neglecting kinetic and potential energy effects, determine at steady state (a) the mass...
Figure provides steady-state data for a throttling valve in series with a heat exchanger. Saturated liquid...
Figure provides steady-state data
for a throttling valve in series with a heat exchanger. Saturated
liquid Refrigerant 134a enters the valve at T1 = 36 degrees Celsius
with a mass flow rate of 0.26 kg/s and is throttled to T2 = -8
degrees Celsius. The refrigerant then enters the heat exchanger,
exiting as saturated vapor with no significant decrease in
pressure. In a separate stream, liquid water enters the heat
exchanger at T4 = 20 degrees Celsius and exits as...
QUESTION 4 (15 marks) Below is a schematic of a car air conditioning system that uses...
QUESTION 4 (15 marks) Below is a schematic of a car air conditioning system that uses R-134a as its refrigerant. Here we will analyze the system under the case of driving through a very hot environment of 40 °C. The interior of the car is kept at 20 °C. Refrigerant leaves the compressor at 1.6 MPa absolute and leaves the condenser as a saturated liquid. The evaporator operates at 400 kPa absolute and the refrigerant leaves as a saturated vapour....
Condenser Compressor An ideal vapor-compression refrigeration cycle is modified to include a counter-flow heat exchanger as shown. Refrigerant 134a leaves the evaporator as saturated vapor at 0.10 MPa and is heated at constant pressure to 20°C before entering the compressor. Following isentropic compression to 1.4 MPa, the refrigerant passes through the condenser and exits at 45°C and 1.4 MPa. The liquid then passes through the heat exchanger and enters the expansion valve at 1.4 MPa. The mass flow rate of...
1. (100 points) A counterflow heat exchanger operates at steady state to transfer heat between air and refrigerant 134a. The air enters at 22°C and 0.1 MPa, then exits at 7°C. The R-134a enters at 0°C at a rate of 30 kg/h by mass, and is a saturated vapor upon exit. Both streams experience no notable change in pressure. (a) Determine the heat transfer rate and associated rate of exergy transfer for the R-134a stream in kJ/h. (b) Evaluate the...
Please use EES only.
In a produce chilling system, air is cooled by being passed over a heat exchanger coil througlh which R-134a flows steadily at a rate of 15 lbm/min. Prior to entering the heat exchanger coil, the refrigerant passes through a throttling valve as shown in the figure below. The R-134a enters the valve as a saturated liquid at high pressure (which will be varied) and leaves at 35 psia. The refrigerant leaves the heat exchanger coil as...
A two-pass shell and tube heat exchanger has an overall conductance l of 450 W/m20 C when used as a condenser for a large air conditioning system. Refrigerant R-134a enters the condenser at 20 kg/ s as a saturated vapor at 70 C and leaves as a saturated liquid. If cooling water enters at a rate of 60 L/s, 10 ° C, determine the outlet temperature of the cooling water and the effective area of the condenser
Problem I: Not applicable for 2017 Problem II: In an R-134a vapor-compression home heat pump, R-134A enters the compressor (75% isentropic efficiency) as a saturated vapor at 200 kPa and leaves at 800 kPa. The refrigerant goes through a constant pressure condenser and leaves as a saturated liquid. The refrigerant then goes through an adiabatic expansion valve enters the evaporator as a liquid-vapor mixture. The mass flow rate of refrigerant is 0.1 kg/s. and Cod A. Write the equation for...
5. Refrigerant-134a at 700kPa, 70°C, and 8 kg/min is cooled by air in a condenser until it exits as a saturated liquid at the same pressure. The cooling air enters the condenser at 1MPa and 10°C and leaves at 17°C at the same pressure. Determine: a) Considering only the Refrigerant as a system, the heat transfer rate of a refrigerant from the condenser in (kl/min). R-134a Tables are attached! b) The mass flow rate of the air required for cooling...
3. An air-conditioning system is shown in Fig.3, in which air flows over tubes carrying Refrigerant 134a. Air enters with a volumetric flow rate of 50 m3/min at 32°C, 1 bar, and exits at 22°C, 0.95 bar. Refrigerant enters the tubes at 5 bar with a quality of 20% and exits at 5 bar, 20°C. Ignoring heat transfer at the outer surface of the air conditioner, and neglecting kinetic and potential energy effects, determine at steady state (a) the mass...
Figure provides steady-state data
for a throttling valve in series with a heat exchanger. Saturated
liquid Refrigerant 134a enters the valve at T1 = 36 degrees Celsius
with a mass flow rate of 0.26 kg/s and is throttled to T2 = -8
degrees Celsius. The refrigerant then enters the heat exchanger,
exiting as saturated vapor with no significant decrease in
pressure. In a separate stream, liquid water enters the heat
exchanger at T4 = 20 degrees Celsius and exits as...
QUESTION 4 (15 marks) Below is a schematic of a car air conditioning system that uses R-134a as its refrigerant. Here we will analyze the system under the case of driving through a very hot environment of 40 °C. The interior of the car is kept at 20 °C. Refrigerant leaves the compressor at 1.6 MPa absolute and leaves the condenser as a saturated liquid. The evaporator operates at 400 kPa absolute and the refrigerant leaves as a saturated vapour....
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