February, 1995
Supermarket Energy Savings of 24%

The LPA was recently installed on the following refrigeration system at Food Town, Takapuna, New Zealand through the Power New Zealand Energy Partnership Program.

Model: 3 rack
Operating hours / month 720

Type: 4-fan air cooled

Refrigerant R-22

The cooling system runs 24 hours a day to provide cooling for the products stored in the store.

The liquid pressure amplifier is a pump, patented by Hy-Save Incorporated of Portland, Oregon, USA and marketed by Hy-Save Australia. The pump is a semi-hermetically sealed unit incorporating a magnetically coupled impeller. Because the motor and impeller are physically separated, motor burnout will not contaminate the refrigerant line, and if the motor does fail, the system will continue to operate.

The LPA can be retrofitted into existing systems, or designed into new equipment for commercial refrigeration and air conditioning.

In traditional systems the liquid must be sub-cooled to eliminate evaporation of refrigerant ("flashing") in the liquid line. The LPA provides extra pressure in the liquid line and allows the pressure of the compressor to be lowered. The increased liquid line pressure eliminates liquid line "flash" gas, resulting in improved efficiency and increased cooling capacity.

In the way the LPA allows the head pressure to be floated with the ambient air temperatures, providing the following benefits:

Increased refrigeration capacity
Compressor efficiency
Reduced compressor run times

Using the LPA, it may be possible to further enhance system performance by injecting a small amount of the pressurized liquid refrigerant into the hot discharge line of the compressor. Liquid injection desuperheats the refrigerant, improving the efficiency of the condenser.

Liquid injection is more suited to systems working in warmer climates, or at high loads.

The system was tuned by the usual refrigeration contractor to extract the best possible efficiency from the system.

The system's energy consumption was recorded for six days before and after the LPA, using the Altech Controls datalogger associated with the refrigeration system. This monitored the total system energy consumption, i.e., compressor and cooling fans.

The tuned system cooling capacity was measured before LPA installation using an ETM 2000 refrigeration analyser. Real-time data was verified before analysis recording.

The cooling capacity was measured over a sufficient time frame to enable a range of system loading and ambient temperatures to be considered for extrapolation into an annual operating profile.

ETM 200 Results
Parameter Units Before LPA After LPA Change
Evaporating Temperature C -15.9 -17.9 12.6% drop
Condensing Temperature C 37.9 26.1 31.1% drop
Discharge Gas Temperature C 76.1 64.0 15.9% drop
Superheat of Suction Gas C 14.6 15.6 6.8% increase
3.79 4.78 26% improvement
Power Output kW 15.4 11.8 22% drop
Altech Controller Results
Location Day kWh (LPA On) kWh (LPA Off) Change
Compressor 1 908 1457

2 965 1453

3 1072 1548

4 1059 1410

5 1022 1202

6 1141 1096

Total 6167 8166 -24%

The simple payback on total expenditure is approximately 12 months, with an net present value of approximately NZ$36,870 over a ten year equipment life. Due to this success, Food Town is now conducting a nationwide store installation program.