ENERGY SAVING
All about parameter settings
Michael Aarup, technical manager at Carel Nordic looks at how paying attention to control settings can improve a system’s energy performance.
T
he main focus today is to save energy, especially in HVAC/R systems, as they consume a large amount of energy. Indeed the potential for energy saving
is quite large, even when simply looking at the current installation and system settings. Settings are how the designer of an electronic device lets users customise the device’s behaviour. Take for example TVs, or smartphones. The default picture settings will hopefully be fine for most users. However, I may like saturated colours rather than a more natural palette. The same goes for the sound, or the appearance of the home screen on my smartphone. This is why you can always find a gear icon somewhere at the top/bottom of your device’s screen to access all the parameters you need for the settings. If we look at a refrigeration installation in a supermarket, with a compressor rack and cabinets, each running with different settings but all connected to a supervisor, it is quite easy to have an overview of how the system as a whole is operating. By looking at the data it will be possible to see what’s working properly and what isn’t. This information can then be used as the starting point to optimise operation and save energy.
The first thing we can always do is to look at the temperature control set points for the different cabinets / cold rooms. For example, why is the set point for the freezer room set to -24°C? The typical answer to is “so we are sure that it is very cold” or “this is the default value for frozen food”! Look up the local temperature standards for frozen food. You will most probably see that it is -18°C. In any case, you can be sure to be compliant with the standard by setting the control set point just 0.5°C lower than that value. This means that all of the cabinets/cold rooms will have an optimised temperature control set point.
Nowadays it is common to see electronic expansion valves managed by a controller, and when these are installed, it is easy to optimise the efficiency of each evaporator. Are the settings optimised for the refrigerant used? Unfortunately, I often see that these are simply left at the default values, which are sometimes maybe not the best for your application. In this case I’m referring to the PID settings and superheat set point. By taking just a small amount of time to improve these settings, you can get much higher efficiency out of the evaporators. In
14 January 2021
www.acr-news.com
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