Air Conditioning Laboratory Project 99. 10

Conservation of Energy:

Power = (mass flow rate)*(work per unit mass w) (eq. 3)

Procedure:

1. 
   Measure the temperature and pressure at the inlet (1) and exit (2) of the compressor.
   

2. Measure the mass flow rate of refrigerant (read from indicator on sensor).

3. 
   Determine the power input to the compressor by reading the current and voltage off
   

OPTIONAL: Read the power from the Power Clamp on the cord, which is connected

to the electrical outlet.
Analysis:

1. 
   Do the measured values of temperature and pressure correspond to what you know is happening in the compressor? Explain in terms of thermodynamic principles.
   
2. 
   Using the measured temperature and pressure values, determine the specific enthalpy h at the inlet and exit using the refrigerant tables in the back of your thermodynamics text.
   
3. 
   Solve for the work done on the fluid using the power input (read from the fan motor) to the compressor and eq. 3.
   
4. 
   Solve for the heat loss to the environment using the values from parts 1 and 2 of the analysis and eq. 2.
   
5. 
   Calculate the power input to the compressor using eq. 3, assuming heat loss can be neglected. Could this be a reasonable engineering assumption? Explain.
   
6. 
   OPTIONAL: Compare the power calculated from reading the voltage and current off
   

To understand the thermodynamic principles involved in the function of a throttling valve. To determine whether approximating the fluid as saturated at the inlet of the valve is a good engineering approximation. To determine the relationship between the quality of the mixture at the exit and the temperature.

The purpose of a throttling valve is to cause a significant drop in the pressure of the fluid. A good example of this is any adjustable valve such as a sink faucet. Along with the drop in pressure comes a drop in temperature. In an air conditioner, it is this temperature drop that is the primary purpose of a throttling valve. As with any device, several engineering assumptions are made in order to simplify the analysis:

(figure 2)

A throttling valve can be modeled as a steady flow system.
Relevant Equations: