A new technology makes it possible to build a cold store with both a low refrigerant charge and a small energy consumption.
Until recently refrigeration systems with a low energy consumption has been synonymous with liquid overfeed systems with a large refrigeration charge. Direct expansion systems using superheat control have been an inefficient alternative, but that has changed. The new technology, called Vapor Quality Control, makes direct expansion systems more efficient than liquid overfeed systems and at the same time having the advantage of a low charge.
The technology is still new, and it is only in Australia the energy efficient systems are widely used. It is a challenge to spread the good stories about the energy efficient cold stores, because most of the owners are not eager to show their efficient plants to competitors, and thereby risk losing a competitive advantage.
However, the technology and experience from Australia are now spreading to Europe where mainly Romania, Germany, and France use the technology.
From a cold store built in the summer 2020 we have this convincing chart which shows how much energy that can be saved when replacing superheat control with vapor quality control.
|The bar chart shows the total electrical consumption for a refrigeration system day by day for September 2020. Until the 16th it was operated with superheat control. After the 19th superheat was replaced by Vapor Quality Control.
Reference list with 30 projects
HB-products is the supplier of the Vapor Quality Sensor and we have now collected a reference list for cold stores and other interesting refrigeration plants operating with Vapor Quality Control. Most of the plant owners do not like to show their facilities and to share their economical benefits with the competitors. However, we have managed to collect a list of 30 projects around the World where the benefits can be proven. Most of the plants are installed in Australia where Scantec Refrigeration successfully have implemented around 20 systems over the last 5 years. Today these cold stores reach an annual specific energy consumption down to 15 kWh/m3. Typical values are above 30 kWh/m3 even for new installations.
Liquid overfeed systems with large refrigeration charges face challenges in many countries where the administrative burden for the safety increases. As an example, in Germany, it is problematic to have more than 3 tons of liquid ammonia and customers like to avoid this. In USA, the annual administrative burden for a large pump circulated system can be up to 250,000 US$ for a cold store.
For systems using large quantities of synthetic refrigerant there is a global warming risk if the system is leaking.
Vapor quality control is a new patented control system for direct expansion systems based on an actual measurement instead of a calculation of superheat. This system increases efficiency significantly especially when the system operates in part load. Read more about vapor quality control and other energy saving technologies.