What is the latent heat of evaporation at -20°F as stated in an Enthalpy Chart?

The latent heat of evaporation, also known as the heat of vaporization, represents the amount of energy required to convert a unit mass of a substance from liquid to vapor at a constant temperature and pressure. At temperatures significantly below freezing, like -20°F, different refrigerants will have specific values for their latent heat of evaporation as indicated in an Enthalpy Chart.

In this case, the value of 583 BTU's is recognized as the correct latent heat of evaporation at -20°F for certain refrigerants, confirming that this figure is a critical reference point for designers and engineers in refrigeration. This value is crucial for calculating cooling loads and for energy efficiency analysis in systems operating under these low temperatures. Using this reference enhances understanding of how much energy needs to be added during the phase change from liquid to vapor, which plays a significant role in refrigeration cycle analysis and system design.

The other provided values do not correspond with the enthalpy data for the temperature in question, which affirms the selection of 583 BTU's as the most accurate representation in the context of the materials and scenarios typically provided in such charts.