Work Done by Expansion Tube Refrigerator

on . Posted in Refinery Engineering

Work done by expansion tube refrigerator is the work associated with the thermodynamic process used in certain refrigeration systems, specifically in relation to gas expansion in an expansion tube or valve.  This process is commonly seen in vapor compression refrigeration cycles, where the refrigerant undergoes phase changes and pressure variations to achieve cooling.

The expansion tube or expansion valve is a critical component where the refrigerant, often in liquid form at high pressure, is allowed to expand rapidly.  This expansion leads to a reduction in pressure and temperature, turning the refrigerant into a cold vapor-liquid mixture.  The work done in this process relates to the reduction in internal energy as the refrigerant cools during expansion.

The context of the expansion tube is primarily an internal energy conversion rather than mechanical work in the typical sense.  In contrast, other parts of the refrigeration cycle, like the compressor, perform actual mechanical work to pressurize the refrigerant before it enters the expansion stage.

Key Points in How this Work is Performed

Isenthalpic Expansion  -  In most systems, the expansion through the valve is considered to be isenthalpic, meaning no external work is done on or by the refrigerant.  Instead, the cooling effect results from the internal energy change during expansion.
Pressure Drop  -  The refrigerant is forced through the expansion tube or valve, where it experiences a significant pressure drop, causing it to cool.  The cooling occurs because the refrigerant uses its internal energy to overcome intermolecular forces as it expands.
Joule-Thomson Effect  -  This cooling effect is a result of the Joule-Thomson effect, where a real gas cools upon expansion if it is below its inversion temperature.  This is a key principle for refrigeration systems.

 

 Work Done by Expansion Tube Refrigerator Formula

\( w  \;=\;  \eta \; \dot m_f \; (H_o - H_i)  \)
Symbol English Metric
\( w \) = Work Done by Expansion Tube Refrigerator \(btu\) -
\( \eta \)  (Greek symbol eta) = Efficiency \(dimensionless\) -
\( \dot m_f \) = Mass Flow Rate \(lbm\;/\;ft\) -
\( H_o \) = Outlet Enthalpy \(btu\;/\;lbf\) -
\( H_i \) = Inlet Enthalpy \(btu\;/\;lbf\) -

 

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Tags: Refinery