Cold Link Africa January / February 2020 | Page 36

CONTRIBUTORS INCORPORATING COLD CHAIN The importance of measuring your refrigeration plant By Kevin Schlemmer, director, CoolCheck In this article, I hope to draw attention to the ‘hidden’ opportunity of improving efficiency in cooling systems and explore some of the challenges and barriers to increase efficiency and reliability of all types of cooling systems from air-conditioning to refrigeration and even heat-pumps. ‘ Cold’ touches our lives every single day, be it the food you eat or the air conditioning in your office. With rising temperatures, air conditioning has become more than a luxury. According to the International Energy Agency, the number of air conditioners in use globally will increase from 1.5 billion to 5.5 billion units by 2050. Ironically, this in-and-of-itself will add to the global warming crisis. By definition, we have created a spiralling feedback loop or ‘Catch 22’. Right now, cooling systems consume a massive 20% of all power generated globally with that percentage likely to increase as the world population increases. The demand for more refrigerated foods will drive the growth in refrigerated cold stores and household fridges. The good news is that the efficiency of the majority of cooling systems can be improved by 10% to 30% by means of low-cost interventions. At an international workshop in 2018, the United Nations (UNIDO) identified this aspect as the most effective and quickest way to reduce carbon emissions. The bad news is that correctly measuring cooling efficiency is not easy and therefore, not commonly found in the market. To address this ‘problem’, a Swedish company developed a system that is quick and easy to use (and is non-invasive). Measuring efficiency is common sense, but not commonplace, unfortunately, therefore many opportunities go undetected and energy is wasted as a result. WHAT IS ‘COP’? For those unfamiliar with the term, ‘COP’ or ‘Co-efficient of Performance’, it is simply a ratio between what you got versus what you paid. A good analogy would be the amount of fuel used by your car to drive 100km. If a cooling system generates say three units of cooling and uses one unit of electricity, then the COP is three. (three divided by one equals three, that simple). We all know that electricity is measured in kilowatts and cooling is also measured similarly. Usually, the letter ‘R’ or ‘r’ is added to the end of the ‘kW’ (kWr) to differentiate it, but in energy terms they are the same. Let’s take a different example; a chiller generates/produces 45kWr of cooling but consumes 20kW of electricity, then the COP is 45/20 which is a ratio of 1 to 2.25 or just simply 2.25. In precisely the same way you want to get the most amount of groceries for every rand at the supermarket, COP is the same – the more cooling kWr you get for every 1kW of electricity the better. The higher the COP, the better! The performance tool that measures efficiency. Chiller performance improved by 20% at Karsten Boerdery in the Northern Cape. THE COP MYTH Kevin Schlemmer in front of a refrigeration plant measuring its performance. 36 www.coldlinkafrica.co.za On face value, this statement contradicts the previous paragraph but let me explain. This is one of the most common misconceptions both within and outside the industry (those that own and operate the systems, and the end- users). The chiller (or refrigeration system) is manufactured in a factory where the actual efficiency must conform to recognised standards. These ‘design’ COP values are then used in the technical manuals and marketing material. People seem to fixate on the quoted COP and assume that because they bought (or sold) a chiller with a ‘high’ COP that they are guaranteed efficient and reliable operation for the life of the plant. This is a misconception, as the stated value of COP is not a static number because when the system is running it changes all the time – every minute of every day! All cooling systems operate in a highly dynamic fashion, meaning that many different things affect the performance and efficiency such as warm (or cold) weather, high cooling load, compressor control (loading and unloading) – the list is long. Between the time that the shiny new cooling system leaves the factory, until it is running on that specific site, with those specific ambient conditions, with those particular installation and maintenance procedures, and so on, a lot of COP can and usually does evaporate. COLD LINK AFRICA • January/February 2020