LPA Science and technology
The benefit of the LPA technology is based on the operation of the expansion valve
and the operation of the expansion valve is directly related to the amount of flash
gas or Freon vapour present and the pressure difference across the liquid metering
device.
A review of the pressure enthalpy chart for R404A at 32 degC will show a 1% vapour (by
weight) will be formed in the liquid line for each 4-psi pressure drop. Comparing
the density of vapour and liquid, shows the relationship between small amounts of
flash gas by weight and we can see that 1 bar pressure drop (14.5 psi) pressure loss
in the liquid line will create 4% flash gas by weight of the volume in the liquid
line. At 30'C condensing temperature this will occupy 44% of the volume in the liquid
line. At 10'C (50F) condensing temperature this would occupy 64% of the volume of
the liquid line. If flash gas is allowed to form, it can have a detrimental effect
on the capacity of the plant, particularly at lower condensing temperatures.
For complete
calculations of the effect of flash gas, contact us for more information and analysis.
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