Integrated Cascading Plant

Abstract

An integrated refrigeration and air conditioning plant working with environmentally friendly natural refrigerant carbon dioxide (CO2) and an ozone friendly non CO2 refrigerant. The low temperature refrigeration is provided by evaporating CO2 and the fluid is used as a secondary refrigerant, predominantly in liquid mode, for medium temperature refrigeration. The heat rejection from CO2 occurs to another upper stage cascaded refrigeration system that operates with a ozone friendly non CO2 refrigerant. Since air conditioning applications require cooling at temperatures higher than refrigeration for food sector, cooling for this range is derived from the non CO2 refrigerant.

Description

FIELD OF INVENTION[0001]The invention relates to refrigeration and air conditioning systems, including such systems when used in a supermarket setting. It specifically addresses the lacuna in integrating seemingly different, but intricately related, domains of cooling requirements at various temperature levels. The objectives are sought to be achieved in a manner that is environmentally friendly, energy efficient and operated in an intelligent way that marries the thermodynamic, fluid dynamic interface at two different refrigerants.BACKGROUND TO THE PRESENT INVENTION[0002]In this document the numbering of refrigerants is in accordance with the protocol recommended by the learned societies relevant to the profession of refrigeration and air conditioning, such as American Society of Refrigeration, Heating and Air conditioning Engineers (ASHRAE), International Institute of Refrigeration (IIR), Australian Institute of Refrigeration, Air Conditioning and Heating (AIRAH), Japan Society of...

AI Technical Summary

Benefits of technology

[0033]A further aspect of use of a compact water cooled heat exchanger and heat recovery is that the size of the heat rejection

Problems solved by technology

The current Australian refrigeration and air conditioning trade practices are unable to reduce the leakages below 10% of initial charge per year.

While this may not appear much, the amount of supermarkets Australia wide is 1500 and therefore the collective damage caused by their leveraging emissions is high.

However, CO2 has not made much of market penetration due to (i) requirements of high pressures in operating systems and (ii) problems associated with its storage in liquid form.

This gives rise to a significant safety hazard (suffocation) if there is any significant leakage of CO2 into the circulating air.

In order to limit the operating pressures, the cascading medium temperature in conventional refrigeration systems is about −10° C. The upper stage cascading with a synthetic refrigerant mandates cooling to be obtained at a maximum of −15° C. At this temperatu

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