Refigeration

Refrigeration Technology

Australian refrigeration leader

Cold Logic is committed to being at the forefront of refrigeration technology – bringing together the leading products from suppliers across the globe with expert local refrigeration design and engineering experience in all facets of applications

Heat Pump Technology

Australia’s first Ammonia Heat Pump energy recovery

Heat Pump Diagram

Cold Logic has installed Australia’s first Ammonia Heat Pump (AHP) at Thomas Foods International (TFI) that turns waste heat rejected from refrigeration plant into 75°C water to offset boiler use. The project was undertaken at TFI’s Lobethal Abattoir in South Australia.

The basic concept of the AHP works on the basis that discharge gas from the high side of the ammonia refrigeration plant is drawn and recompressed by a high pressure compressor. This elevates the pressure and increases the temperature which in turn is passed through a heat exchanger where it transfers its heat to water on the other side.

 

Thermosiphon Oil Cooling in refrigeration screw compressors

Why install thermosyphon oil cooling? The simple answer is to avoid power, energy and maintenance costs associated with liquid injection oil cooling on the refrigeration compressors. Liquid injection oil cooling typically consumes 5% to 15% of the compressor power to recompress injected refrigerant. Thermosyphon cooling does not consume compressor power.

Thermosyphon oil cooling is an indirect cooling method which uses refrigerant condensate as the cooling medium in an external heat exchanger. The refrigerant passively circulates from the high pressure receiver through the heat exchanger, cooling the oil, and then returning as vapor and liquid to the receiver. Thermosyphon equipment generally adds 5 to 7% to the original cost of the machine, but the energy savings usually result in a less-than-one-year payback if the machine operates most of the year, or electric rates are higher.

Previous oil cooling systems were direct injection of refrigerant or indirect cooling with water or glycol. The amount of energy used by liquid injection oil cooling is approximately 5-15% of the kilowatts of the liquid injection machines, and the machines must be increased in size to account for capacity reduction. Indirect cooling with water or glycol utilizes a heat exchanger with an external cooling tower or evaporative condenser.

When to Apply:

  • When liquid injection is used to cool large compressors.

  • When reducing refrigerant, condensing pressure is limited by liquid injection cooling without installation of a liquid injection pump. The pump uses energy and improves the economics of thermosyphon oil cooling.

Key Engineering Concepts:

Liquid injection oil cooling works by expanding high-pressure refrigerant liquid to an intermediate pressure and injecting it into the compressor.

  • Some liquid refrigerant flashes to vapor during expansion and the rest evaporates as it cools the compressor.

  • Thermosyphon oil cooling uses a heat exchanger near the compressor sump to cool the oil.

  • A high pressure pilot receiver collects refrigerant liquid which falls by gravity into the oil heat exchanger.

  • The refrigerant evaporates and buoyancy drives the flow to the condenser.

  • The thermosyphon oil cooler may require an additional condenser.

  • Condenser fans will use more energy, but much less than compressor.

Contact Us / Adelaide

Head Office
24 Francis Street, Port Adelaide South Australia 5015
PO Box 74, Port Adelaide
Telephone 08 8240 3333
solutions@coldlogic.com.au

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