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Natural Refrigerants – A Clean Calculation

From the CFC ban and the Kyoto protocol to the EU regulation on fluorinated greenhouse gases, increasingly, national and international laws are limiting the use of harmful refrigerants. Against this background, operators are confronted with the question of the ecological and economical characteristics of refrigeration methods. Dr Rob Lamb, Marketing Director at Star Refrigeration, and eurammon member, speaks to Climate Control Middle East about the important factors that go into an economic calculation.

| | May 18, 2017 | 3:15 pm
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TO COMPARE THE ECONOMIC EFFICIENCY OF DIFFERENT SYSTEMS, YOU NEED TO LOOK AT THE OVERALL COSTS. WHAT ARE THE RELEVANT FACTORS FOR THE CALCULATION OF THE SO-CALLED LIFECYCLE COSTS?

When comparing different cooling solutions, it is important to look at the overall costs. Cooling systems operate at design conditions for only a few hours per year. Understand the cooling load profile and ambient temperature profile for a project to enable calculations to be carried out to show differences in performance between two or more systems. Modern ammonia systems typically incorporate energy-enhancing features, such as variable speed compressor motors and fans. They also have heat exchangers with close temperature approaches and control systems that enable the evaporating and condensing temperatures to vary with load and ambient conditions.

It is common to find that synthetic solutions need replacing after 10 years, and this should be built into any lifecycle comparison

The combination of these energy enhancements typically shows energy benefits over alternative solutions using synthetic refrigerants. Plant-life expectancy should also be built into lifecycle calculations. Ammonia systems are designed for an operating life of 20+ years due to the quality of materials and components used, and the methods of construction. Solutions using synthetic refrigerants are typically built to a price and with a shorter operating life. It is common to find that synthetic solutions need replacing after 10 years, and this should be built into any lifecycle comparison. There is also the uncertainty of HFC refrigerants to consider, and it may mean that refrigerant replacement needs to be considered sometime in the future.

THE RELATIVELY HIGH INITIAL INVESTMENT COSTS FOR SYSTEMS USING NATURAL REFRIGERANTS ARE COUNTERBALANCED BY LOWER OPERATING COSTS AND A LONGER LIFECYCLE. WHAT DOES THAT MEAN FOR THE AMORTISATION TIME?
Investment in natural refrigerant systems should be seen as a long-term investment, particularly when using ammonia. It is typical to find a return on the additional investment requirement of 3-5 years. After this point, the natural refrigerant systems will continue to deliver reduced operating costs over the lifetime of the plant.

NATURAL REFRIGERANTS ARE VERY COST-EFFICIENT. HOW DO CONTENTS AND LEAKING AFFECT THE OPERATING COSTS?
The toxicity and/or flammability of natural refrigerant systems (with the exception of carbon dioxide, which is neither toxic nor flammable) mean that mitigating the risk of leakage at the design and manufacturing stages is of key importance. Historically, leakage rates from ammonia systems have been negligible, and topping up of refrigerant has typically been the result of service work, where it has been necessary to remove some of the refrigerant before carrying out work. The cost of any replacement of natural refrigerant is typically less than 10% of HFC gases, and this gap is set to widen with the introduction of more expensive HFO and HFC/HFO blends.

IN SPITE OF THEIR HIGHER INITIAL INVESTMENT COSTS, AMMONIA-BASED SYSTEMS FOR LARGESCALE INDUSTRIAL REFRIGERATION HAVE BEEN ESTABLISHED FOR QUITE SOME TIME. NATURAL REFRIGERANTS ARE FINDING THEIR WAY INTO MORE AND MORE SECTORS OF THE AIR CONDITIONING INDUSTRY, FOR EXAMPLE, SMALLER APPLICATIONS WITH UP TO 200 KW. WHAT DO YOU THINK ARE THE REASONS FOR THIS DEVELOPMENT, AND WHERE IS THIS TREND LEADING THE INDUSTRY?

Uncertainty over the future of synthetic refrigerants is a key driver behind the growing interest in natural refrigerants for smaller applications. End-users don’t want to invest in equipment that may need replacing or retrofitting in the next 5-10 years. Natural refrigerant solutions provide certainty in terms of not being subject to any future phasedown or restriction on uses.

Historically, leakage rates from ammonia systems have been negligible. Historically, leakage rates from ammonia systems have been negligible

Developments in natural refrigerant technology have also helped to grow interest, as it has meant that natural refrigerant components and equipment have become more affordable. Particularly, carbon dioxide systems are price-attractive and have, therefore, resulted in growing numbers-for example, in retail and commercial applications. Natural refrigerants are a viable alternative to synthetic solutions also for small capacity systems.

IN YOUR OPINION, WHICH TOPICS REQUIRE THE MOST INFORMATION ON THE MARKET TO CONVINCE THE DECISION-MAKERS OF THE LONGTERM PROFITABILITY OF NATURAL REFRIGERANTS?
Demonstrating a reasonable return on investment with natural refrigerant systems, and also the uncertainty over synthetic refrigerants are to two key drivers in convincing customers to move to natural refrigerants. Whilst initial cost may be higher, when all aspects of the lifecycle cost are considered, including efficiency, longevity and long-term availability, natural refrigerants make sense.


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