1. A LOW CARBON DEFROST SYSTEM Tom DAVIES, Robin CAMPBELL, Varun THANGAMANI Frigesco Ltd., Innovation Centre, University of Exeter Tom@frigesco.com 15 th Intnl Refrigeration and Air Conditioning Conference, Purdue, 2014

2. EXISTING DEFROST METHODS Electric Hot gas Cool gas Warm liquid Reverse cycle ALL USE EXTRA ENERGY TO MELT ICE AND THEN TO RE-CHILL Some use thermal storage

3. FLASH DEFROST REQUIRES A HEAT STORE INSERTED IN THE LIQUID LINE LEAVING THE CONDENSER REQUIRES 3 SOLENOID VALVES + PIPEWORK DOES NOT USE EXTRA ENERGY

4. NORMAL OPERATION & HEAT STORE ON CHARGE

5. SUBCOOLING DURING CHARGE

6. START OF DEFROST

7. EVAPORATOR TEMP DURING DEFROST

8. HEAT STORE DEPLETED

9. HEAT STORE RECHARGED

10. POSSIBLE COLD CHAIN APPLICATIONS LARGE SYSTEMS – WAREHOUSES TRANSPORT SYSTEMS SUPERMARKETS AND CONVENIENCE STORES – WALK-INS RETAIL DISPLAY CABINETS (RDCs) DOMESTIC FREEZERS ______________________________________________ PLUS AIR SOURCE HEAT PUMPS

11. TESTS ON: Supermarket retail display cabinets - 4.8m worldwide. Cold Rooms - over 2.5m worldwide, 900k in large supermarkets, 300k in fast food (MacDonalds, Starbucks, etc) plus hospitals, schools, restaurants. Air source heat pumps, rapidly growing market. Over 2m units sold in Europe in 2010.

12. RDC TESTS 2.6m HALF GLASS DOOR PLUS OPEN WELL (R404A) BOTH REFRIGERATION CIRCUITS MODIFIED TO TAKE HEAT STORE MODULES COULD BE RUN WITH EITHER ELECTRIC DEFROST OR FLASH DEFROST 24hr TESTS TO COMPARE ENERGY CONSUMPTION TO EN23953:2005 STANDARD AT CC3. FLASH DEFROST REDUCED ENERGY CONSUMPTION BY 40% WITH 6 DEFROSTS PER DAY.

13. RDC TESTS – AVERAGE PRODUCT TEMPERATURES

14. WALK-IN TESTS 8m 3 STOREROOM WITH SIMULATED LOADS REFRIGERATION CIRCUIT MODIFIED TO TAKE HEAT STORE MODULE (R404A) COULD BE RUN WITH EITHER ELECTRIC DEFROST OF FLASH DEFROST 24hr TESTS TO COMPARE ENERGY CONSUMPTION FLASH DEFROST REDUCED ENERGY CONSUMPTION BY 20%

15. ELEMENTS OF WALK-IN RIG

16. WALK-IN TESTS – PRODUCT TEMPERATURE SWINGS

17. DAILY ENERGY CONSUMPTION RDCElectric defrostFlash defrost DEC (KWh/24h)52.2631.87 REC RC (KWh/24h)66.6639.03 TEC (KWh/24h)118.9270.90 WALK-INElectric defrostFlash defrost TEC (KWh/24h)360288

18. BENEFITS OF FLASH DEFROST Flash defrost eliminates the use of electrical power for melting ice Flash defrost limits the temperature rise in the air coil Flash defrost reduces temperature rises in the product Flash defrost reduces energy consumption in post-defrost re-chilling phase Flash defrost creates the opportunity to operate at higher evaporator temperatures Flash defrost allows more frequent defrosts

19. Questions? —