How to utilize waste heat from refrigerators in a smart and effective manner?


The inefficient use of energy, such as waste heat, is an unacceptable luxury in an environment driven by sustainability principles and climate change mitigation trends.

A project for waste heat utilization from refrigerating units, in fusion with solar energy, has been implemented in the industry for processing and sale of meat “Milivoj Medven”, situated in Gornje Prekrižje, Krašić (Croatia), for hot water supply purposes. The objective of the project was the reduction of extra oil fuel consumption for hot water supply production. During the plant reconstruction in 2010, they came across an inventive solution to utilize waste heat from the refrigerator units which would otherwise go to waste.

Before the project was launched, the boilers were equipped with 50 and 100kW of thermal capacity run by extra light fuel oil with 2 x 4000 l storage tanks. Within the project, additional applications were installed: two 12 600 l storage tanks, 300 m2 flat-plate solar collectors, four heat exchangers on the cooling circuit, two heat exchangers of 150 kW thermal capacity for hot water supply, pumps, safety equipment and full system and drive control with remote measurement via Internet. Extra fuel oil boiler of 50 kW has been replaced by a 100 kW boiler.   

Undertaking these energy efficient measures, the consumption of extra light fuel oil has decreased by 85 % together with 192 t less GHG emissions. The shares in covering hot water needs are: 29 % from solar collectors, 56 % from recovery systems and 15% from boilers. The project has been co-financed using the ESCO model structure and the annual savings are estimated around 42 000 €.