Carbon dioxide

Climate-conscious shoppers may buy local food and try to cut packaging waste, but those efforts could be negated by potent greenhouse gases leaking from supermarket fridges.

Italian OEM Epta has released results from its Life-C4R (Carbon 4 Retail Refrigeration) project, summarizing three years of data from seven European supermarkets testing commercial CO₂ (R744) refrigeration systems.

This summer’s heatwave in the UK has created havoc for many supermarkets with multiple stories of refrigeration system failures, lost stock and lost sales. All refrigeration technologies have been affected by this extreme weather, but now, with so many retailers using CO₂ systems, Daniel Clark owner and MD at Preston-based CO₂ systems manufacturer Isentra, asks whether 130bar transcritical systems have now become a necessity?

In both technical and non-technical literature, fluorine-containing (HFC) refrigerants are increasingly referred to as ‘chemical’ or ‘synthetic’ refrigerants in contrast to the so-called ‘natural’ refrigerants. Generally ‘chemical’ is now seen by some as being ‘bad’ and is contrasted with ‘natural’, which implies ‘good’.

Mexican cold-storage operator Frialsa is leading its country’s adoption of NH₃ /CO₂ systems that are safer and 15%-20% more energy efficient than conventional ammonia equipment.

A developed society cannot function without refrigeration. At home, in food production and storage (e.g. frozen foods, yogurt, and or coffee), in the production processes of the automotive or chemical-pharmaceutical industry, or for air conditioning – wherever you look, “cooling” is essential. Industrially generated “coldness” is a central pillar of modern life. In Germany, 14 % of the primary energy consumed is used for cooling purposes. Negative influences on the environment can be reduced by using natural refrigerants.

The decision as to which refrigerant should be used in a refrigerating or air-conditioning system is based on the major criteria of safety, costs and environment protection. But against the background of constantly increasing energy prices, the energy consumption of a system also plays an increasingly important role. Ideally, the chosen refrigerant should have excellent thermodynamic properties, high chemical stability and good physical characteristics. Furthermore, it should have no or only a negligible impact on the environment, while also being inexpensive and available worldwide.

The Defense Commissary Agency (DeCA) currently operates a 117,000-square foot commissary in San Antonio, Texas. The store is located in the community service area of the Lackland Air Force Base and is surrounded by other retail stores, banks, schools, and housing.

Climate change, greenhouse effect and global warming – scarcely any other issue is so omnipresent and so controversially discussed in the 21st century. Those who are convinced in doubting that climate change is man-made refer to various eras in the history of our planet where the earth has heated up or cooled down drastically even without any contribution on our part. In future too, they see climate change as the result of natural causes, including among others a changed ellipsoid orbit of the earth around the sun.

I was going to call this post “Playing With Fire” but didn’t for obvious reasons. Anyways, in my last post we saw how CO₂ (R744) can be used in both a traditional sub-critical as well as in trans-critical cycles which operate almost backwards to each other. Also, when I typed in trans-critical without the hyphen, Spell Wreck asked me if I meant to type ‘transatlantic’ instead. Um no, but it did remind me of a little bit of history to touch on before we move onto R290. I apologize for the digression but I think you will find it interesting.

The ban on the use of R134a in mobile air-conditioning systems within the EU has triggered a series of research projects. Apart from the CO₂ technology (page 35), new refrigerants with very low GWP values and similar thermodynamic properties as R134a have been developed.

Kysor/Warren, a division and brand of global refrigeration equipment maker Heatcraft Worldwide Refrigeration, is optimistic that deployment of natural refrigerant technologies will expand in the U.S., but the company admits there are some obstacles to overcome.

Fluorocarbon refrigerants are synthetic chemicals which usually have a high global warming potential, and some still have the potential to cause damage to the ozone layer as well if released to the atmosphere.