Many energy audits have been undertaken at horticulture farms throughout Queensland. The Energy Savers Program. The producer washes and cools pineapples from field temperature for distribution. An audit of site energy consumption considered initiatives to reduce wet tropics packing shed running costs, particularly refrigeration energy utilisation.
The audit found a number of issues with the refrigeration system that was no longer operating as designed. Due to water pump and trough failures, the evaporator no longer used water as a cooling medium but only air. This reduced the efficiency of the original non-finned evaporator as it does not have the required surface area to satisfy an air-only heat transfer method.
The following projects were completed after the audit:
- Upgrading the existing evaporator to two heavy-duty units equipped with electronic expansion valves (EEV) allowed for highly adaptive heat absorption;
- Refrigerant conversion from R22 to R134A. Due to HCFC phase out, using R22 is no longer economical and any need to re-gas system could outweigh potential savings. While there is a performance penalty associated with the R22 to R134A conversion, the system will still satisfy new design requirements with an added benefit of lower compressor input power; and
- Additional condenser fan controls. Due to the R134A conversion, the condenser is now oversized and will require improved fan control with the added benefit of lower condenser fan runtime.
The project has reduced the refrigeration energy consumption by 50 per cent with over 50MWh of annual energy savings, nearly 22kW of demand savings. The project is saving $20,000 per year with a payback period of 1.3 years.
Photo by Garry Knight HERE.