TINE Tunga’s new heat pump, which has been developed by Cadio AS in collaboration with the Norwegian University of Science and Technology (NTNU), can generate hot water up to 85°C, while simultaneously enabling cooling down to 3°C. Innovation Norway, which is the Norwegian Government’s leading instrument for supporting innovation and development within Norwegian industry, contributed with financial support for the project.
60% energy savings for the cooling of milk with CO2 based heat pumps
The use of CO2 as a refrigerant is significantly more environmentally friendly than HFC based refrigerants, with its low global warming potential and increased energy efficiency compared to other technologies. For instance, a study on energy efficient cooling of milk was put forward by Norwegian researchers Rekstad and Hafner in 2012, showing that a transcritical CO2 heat pump used for cooling milk and heating hot water could save 60% in energy use compared to a standard R134a heat pump with electric heating.
TINE’s heat pump water heater will deliver 660,000 kWh in a year
TINE’s transcritical CO2 sanitary hot water heat pump, which came into use in September 2012, has shown optimal energy efficiency. The heat pump consists of a gas cooler, two evaporators in parallel, a semi-hermetic piston compressor, and a storage tank for managing system variations. It is more than capable of keeping up with the dairy’s heating and cooling requirements:
- The heat pump has a heating capacity of 160 kW and produces 1,800 litres of hot water an hour.
- The COP of the heat pump over a week is measured at 3.0. Taking into account the energy savings from not using an ice water compressor, the total COP is measured at 4,5.
- In a year the heat pump will deliver 660,000 kWh.
- The system functions under both high and low pressure. At the cooling side (low pressure side) the pressure is at 32 bars and for the warmer side (on the higher pressure side) it is at 100 – 110 bars.
- In the last 5 years great advancements have been made in equipment that can take up to 125 bars which significantly increases efficiency.
The dairy has a hot water heating necessity of 50 – 69 m3 per day, and experiences significant variations throughout the day. The system has a 400-litre hot water storage tank to address theses variations in demand.
The annual heating demand for water at Tine is approximately 1.41GWh, and the heating demand for water is covered by the CO2 heat pump and district heating system. When the heating need is greater than the heat pump’s capacity, district heating is used to cover the remaining need.
New technological advancements could see industry adopt more CO2 heat pump water heaters
As Berntsen, Eikevik and Jenssen, from NTNU (Norges teknisk-naturvitenskapelige universitet) highlight in their research on the optimisation of the heat pump at the Tunga factory, it has been due to the challenges with regard to the high working pressure of CO2 that until now the refrigerant has mainly been used on the low-pressure side of cascade systems.
The lack of high-pressure components has been another limiting factor in the development of CO2 heat pumps. However, heightened interest in R744 has led to the technological improvement of transcritical CO2 heat pumps. As illustrated, above, thanks to new developments, it is now possible to deliver hot water with a temperature of 80°C while simultaneously providing cooling of ice water, which is especially significant for food processing industries.
As Norway’s largest producer, distributor and exporter of dairy products, TINE has been nominated as the #1 cooperative by size by the International Cooperative Alliance. However, as exemplified, TINE is also leading the way with regard to developing energy efficient technologies, which bodes well for further use of heat pump water heaters in industrial applications.
