As part of the Greenhouse Neutral House initiative, ANU is developing a hybrid thermal air conditioning system for residential use. The system is capable of solar air conditioning in summer, solar space heating in winter and solar water heating all year round using commercially available collectors.

There are a number of methods that are capable of providing cooling from solar energy sources, but few methods are well suited to domestic use. Absorption and adsorption coolers are bulky and expensive. Evaporative coolers have high water consumption and high electricity consumption. The ANU system is based on the ejector jet pump principle. It is easy and inexpensve to mass produce, very reliable and has performance similar to an absorption chiller.

This project is funded internally and we are currently constructing a proof-of-concept device which we expect to have running during 2008. External funding will then be sought.

Project Background

The ejector principle has been known for around 100 years. Otherwise known as jet pumps, early ejectors were used to evacuate the condensors in steam power plants. Since jet pumps are capable of generating low pressure, they soon became used for refrigeration purposes. It was not uncommon for these units to run continuously for twenty years with little maintenance. The invention of the high performance heat pump relegated the ejector refrigerator to applications where waste heat was available (ships, power stations, processing plants) where they are still in use.
Recently, interest in ejector systems has been renewed with research into new refrigerants, and a deeper understanding of how ejectors work. There are still a number of outstanding areas of understanding and development in the areas of dynamic ejectors, smart control systems, energy storage and CFD modelling and laser visualisation.

Ejector circuit

Ejector construction