The subject of ENERGY SAVING has become a fundamental aspect in the field of commercial refrigeration and air-conditioning.
This is true above all for supermarkets, fresh produce markets, as the reduction of energy wastage represents the most effective way to contain costs and achieve better competiveness. Furthermore, the adoption of techniques and methods aimed at SAVING ENERGY in the installation also means embracing a social responsible policy in relation to all stakeholders that interact with the company: shareholders, workers, customers, suppliers, the environment and society.
Businesspeople who are sensitive to environmental issues and the notion of ENERGY SAVING have made these concepts an integral part of their corporate identity, with the conviction that the sustainable business model offers greater guarantees of long-term development, the opportunity to enjoy the advantages of eco-efficiency in terms of competitiveness, as well as to share in the benefits of “territorial competiveness”.
This is just one way we can save you 20% on your electrical bill….. We have achieved 67% in some cases using various new ways in the design or upgrade of you refrigeration systems.
Typical energy consumption of a supermarket.
Typical energy consumption of a fresh produce facility
It has been widely demonstrated that more than 70% of power consumption in a fresh produce facility is due to the cold storage of food (compressor packs, showcases, cold rooms, processing rooms).
Action taken in this area therefore allows significant energy savings to be achieved.
To fit refrigeration utilities (showcases, cold and freezer rooms) with electronic expansion valves for the control of flow of refrigerant to the evaporators, combined with modulation control of the condensing pressure on compressor packs, so as to optimise operation and efficiency when the outside temperatures are especially favourable (in winter).
It has been found that over a period of a year, the outside air temperature in normally lower than 20ºC at least 65% of the time.
In a traditional installation with mechanical thermostatic valves (TEV), this data has no influence, as the entire installation is forced to operate in conditions in which the condensing values must be fixed so as to allow the correct operation of the mechanical expansion device.
In an installation with electronic valves (EXV), however, as these operate completely independently from the pressure difference, floating control of condensing temperature is possible, that is, the condensing temperature is constantly adjusted based on outside temperature.
This in turn allows significant ENERGY SAVINGS, whilst maintaining the suction pressure (and consequently the temperature of showcases) stable, and reducing the condensing temperature from 45 to 20ºC, for example, when the outside conditions allow. Overall energy savings of up to 20% can be achieved in this way.
Normally, in fact, each one degree decrease in condensing temperature corresponds to energy savings of 2%. The manufacturers of compressors also provide tables that show the considerable increase in COP (coefficient of performance) of a compressor in a refrigeration unit as the condensing temperature decreases. (See fig. 3)
COP values with evaporating temperature (-10ºC)
The concept is actually quite simple, as high condensing temperature lead to an increase in the compression ratio, and consequently a reduction in cooling capacity (and thus a decrease in COP) and an increase in power input.