School of Engineering & Advanced Technology (SEAT) in conjunction with the Institute of Refrigeration, Heating and Air-Conditioning Engineers of NZ (IRHACE)

Seminar Series 2018


SPEAKER: Tom Davies, Emeritus Professor, University of Exeter, UK

DATE:                        Monday, 26 March, 2018

TIME:                         12:00 noon to 13:00 pm

VENUE:                      Either Face-to-Face or Webinar

Face-to-Face -  RC2.143 (Presentation Lab, Riddet Complex, Massey University, Palmerston North) – see attached map, parking in Orchard Road car park, Riddet Complex is at grid D10, use the Institute of Food Science & Technology entrance, RC2.143 is on the 2nd level             

Webinar - via an Adobe Connect meeting (to join from PC, Mac, iOS or Android); please connect a few minutes early to allow time to configure microphone and video.

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Get a quick overview:

Aircoils used in freezer systems and air source heat pumps need periodic defrosting, a process which consumes significant amounts of energy (often electrical) and commonly creates undesirable effects in frozen food storage equipment and a reduction in COP of heat pumps. The talk describes the operation of a low carbon method of defrosting aircoils which does not require extra energy (it stores and then uses surplus energy in the liquid refrigerant leaving the condenser) and also reduces side effects such as large temperature variations in frozen food and “steaming”. Experimental results obtained from controlled laboratory tests on retail display cabinets, walk-in cold stores and an air source heat pump will be presented showing typical energy reductions of around 20%. Retrofitting in several operational supermarkets revealed that a typical commercial aircoil operating well as an evaporator does not usually perform well when operating as a condenser, an essential requirement of the new defrost system, in which a thermosyphon flow of refrigerant transfers heat from a heat store to the frosted aircoil. There is now a need to design aircoils which will uniformly distribute a two-phase mixture of refrigerant between the multiple  pipe sections connected to the inlet manifold so that defrost is uniform over the entire tube bank.

Tom Davies has been an academic for more than 40 years, mainly in the UK.  He is currently Emeritus Professor at the University of Exeter.  His research and consultancy has focussed on wide range of technological heat transfer and fluid flow problems and have led to more than 150 scientific publications. In 2010, he began development work on an energy-free defrost system and formed Frigesco Ltd to commercialise the technology. Frigesco Ltd has won awards in three competitions in 2014 - the Annual RAC Cooling Industry Awards (Refrigeration Innovation – component or process), the Monaco CleanEquity Awards (Environmental Award), and the CleanTech Innovate Awards (Best in Show).