This is an abbreviated version of the lecture delivered by SAIRAC centres in Johannesburg , Durban , Port Elizabeth and Cape Town . Due to its importance and length , the entire lecture will be run in four parts in the succeeding issues of Cold Link Africa .
ASSOCIATIONS
The journey to a better world : a refrigeration perspective
The Dreosti Memorial Lecture presented by Andy Pearson , edited by Eamonn Ryan
This is an abbreviated version of the lecture delivered by SAIRAC centres in Johannesburg , Durban , Port Elizabeth and Cape Town . Due to its importance and length , the entire lecture will be run in four parts in the succeeding issues of Cold Link Africa .
Supplied by SAIRAC Cape Town centre Image by © Cold Link Africa
INTRODUCTION
Engineers have always balanced optimism with realism . They recognise the flaws in current systems but remain hopeful about their ability to drive progress . Over the past three decades , the refrigeration industry has actively pursued innovations to address environmental concerns associated with traditional systems . Despite notable advances , issues like climate change , energy security , political instability , resource depletion , and population growth continue to challenge the sector . This raises critical questions : " Have we done enough ?" and " What more needs to be done ?"
Reflecting on four decades of technological and political developments , it is clear that significant investments in research and development have been made . Yet , progress often seems incremental rather than transformative . Innovations frequently involve substituting one refrigerant for another rather than rethinking the cooling process . While new technologies have emerged , they often address only parts of the cooling process and fall short of their promises .
A crowded house in Cape Town .
MAIN CHALLENGES IN REFRIGERATION SYSTEM DESIGN
Over the past thirty years , the refrigeration sector has faced three main challenges :
• Environmental impact : Addressing the ozone depletion and global warming potential of refrigerants has been a major focus , regulated by agreements such as the Montreal and Kyoto Protocols .
• Performance efficiency : Energy efficiency impacts both operational costs and environmental emissions . High energy costs drive the need for more efficient systems , but initial investments can be daunting .
• Safety and reliability : Compliance with national and international safety regulations is crucial to prevent accidents and ensure system reliability .
International agreements often progress slowly . The phase-out of ozone-depleting chlorofluorocarbons ( CFCs ) will stretch over 40 years , ending in 2030 with a complete ban on substances like R-22 . Energy efficiency improvements are similarly
Left to right : SAIRAC national president Robert Fox , Dr Andy Pearson receiving a memento of the occasion , and SAIRAC Johannesburg chairman Gregory Grobbelaar . affected by fluctuating energy prices and the upfront costs of new technologies . Safety measures , while essential , can be hard to justify financially despite their importance .
ACHIEVEMENTS AND INNOVATIONS
Key achievements include the Montreal Protocol , adopted in 1987 , which is hailed as one of the most successful international treaties . Initially focused on CFCs , the Protocol has been amended to address hydrochlorofluorocarbons ( HCFCs ) and hydrofluorocarbons ( HFCs ) through the Kigali Amendment of 2016 . This amendment extends the Protocol ’ s scope to include high global warming potential substances , adapting its successful model to address climate change .
The transition in refrigerants has occurred in three phases :
• From CFCs to HCFCs : This shift aimed to reduce ozone depletion potential but was only a partial solution .
• From HCFCs to HFCs : HFCs like R-134a were introduced as chlorine-free alternatives . However , their high global warming potential exposed limitations in the Kyoto Protocol ’ s regulations .
• From HFCs to HFOs : Hydrofluoroolefins ( HFOs ) with shorter atmospheric lifetimes have emerged as the latest alternative , though they bring new environmental concerns about their breakdown products .
Each transition has introduced technical challenges , from adapting technologies to new refrigerants to addressing safety issues with substances like R-1234yf . While each step has been difficult , it has paved the way for more complex solutions in the ongoing quest for better refrigeration technologies .
REFINING REFRIGERATION : PROGRESS AND COMPROMISES
The evolution of refrigeration technology has seen substantial achievements but also numerous setbacks . Early refrigerants like R-404A , a blend of R-125 and R-143a , were effective in addressing ozone depletion but had high global warming potentials . Although R-404A was a suitable alternative to R-22 in the 1990s , it fell out of favor as the focus shifted to low GWP fluids .
Balancing ozone depletion and global warming has led to compromises . Simple metrics like GWP ratings do not capture the full spectrum of environmental impacts , making the transition an ongoing process . The GWP logarithmic scale helps set regulatory standards , guiding the shift toward more environmentally friendly options .
Advancements in natural refrigerants have gained traction . Hydrocarbons like propane
( R-290 ) and isobutane ( R-600a ) are effective and safe alternatives , with R-600a becoming widely adopted . Carbon dioxide , though effective in commercial applications , remains costly and less efficient compared to HCFCs and HFCs . Ammonia has seen a resurgence in industrial applications , where modern systems have mitigated leakage risks .
The introduction of air cycle systems , though historically significant , remains niche due to its limited commercial use .
EVALUATING PROGRESS AND FUTURE DIRECTIONS
As we approach 2025 , it ' s essential to assess refrigeration technologies in the context of broader climate agreements . The Vienna Convention and Montreal Protocol , along with regulations like the European F-gas regulations and the U . S . AIM Act , have successfully addressed ozone depletion . Ozone levels are expected to recover to 1980s levels by around 2060 , a significant achievement .
However , addressing global warming has proved more challenging . The Paris Agreement aims to limit temperature rise to 1.5 ° C above pre-industrial levels , but current emission reduction forecasts fall short . Optimistic scenarios suggest only a 10 % reduction in emissions by 2030 , which is insufficient to meet the targets .
In refrigeration , progress must be evaluated based on environmental impact , efficiency , and safety . R-600a remains the dominant and safest option for domestic refrigerators , with minor efficiency improvements expected . Industrial systems have seen enhancements with low-charge ammonia plants , and carbon dioxide has proved effective in industrial freezers . Ongoing development is expected to address remaining gaps .
FUTURE REFRIGERATION TECHNOLOGIES
Predictions about CO 2 in refrigeration have largely proved accurate . While CO 2 has seen success in freezers and heat pumps , its use in other industrial applications remains limited . Ammonia is typically more costeffective and efficient compared to CO 2 systems , which , despite low initial costs , have high maintenance expenses and shorter lifespans .
Commercial refrigeration has made notable strides . Various CO 2 systems , including CO 2 as a volatile secondary refrigerant and transcritical CO 2 systems , have proved effective . Retailers have adopted propane in display cases and hydrocarbon systems in smaller appliances .
For large water chillers , refrigerants like R-134a , R-1234yf , R-1234ze ( E ), and R-1233zd ( E ) are prevalent , while ammonia
10 www . coldlinkafrica . co . za COLD LINK AFRICA • November / December 2024