Liquid Pressure Amplification
Patented in the USA, Liquid Pressure Amplification (LPA) was developed to allow refrigeration equipment to operate at more efficient operating parameters.
It is well known that refrigeration efficiency improves as discharge pressure / condensing temperature is reduced, this is commonly referred to as floating head pressure and is advocated in many publications.
In most refrigeration systems the limiting factor is maintaining a flow of good quality refrigerant to the expansion valve. Liquid Pressure Amplification (LPA) pumps liquid refrigerant from the condenser to the expansion valve, by maintaining this critical flow compressor discharge pressure can be reduced, increasing refrigeration efficiency by 20-40% to give a corresponding reduction in energy consumption.
For every 1 deg c that condensing temperature is reduced refrigeration efficiency is increased by 2-4%. Following modification and during periods of low ambient temperatures it is not unusual for the condensing temperature to be reduced by 15 - 20 deg c.
Delivery of refrigerant to the expansion valve is also improved, for optimum efficiency the expansion valve requires refrigerant in its liquid state. In many systems the pressure drop in long pipework connecting the condenser to the evaporator causes refrigerant to evaporate, this is called "flash gas" and reduces the cooling effect in the evaporator.
It is not unusual for the compressor to be adjusted to operate at a lower temperature to overcome this effect, which increases evaporator capacity but reduces compressor efficiency, sometimes by as much as 10-15%. Once operating with Liquid Pressure Amplification (LPA) the compressor can be returned to its' design conditions.