CHILLERS
Future proofing chillers
Trevor Dann of Thermozone considers the refrigerant dilemma in terms of longevity of use.
W
ith the impact of the F-Gas Directive revision of 2014 and its associated phase down of HFC refrigerants, now in the late Spring of 2017 the first signs of supply shortages ahead are being felt. Whereas arguably a licence for refrigerant manufacturers to print money, at the expense of equipment users (and un-wary contractors !), already 2017 has seen compound cost price rises ~ 50% affecting supply of common service refrigerants used in water chillers – R134a; R407C; R410A. And this is before the large step down in available volume from next year (2018) as the next stage of phase down is implemented. Of concern to all chiller suppliers and maintainer should be what to offer clients, both those with existing equipment and those procuring new equipment.
The F-gas phase down period will increasingly affect not only new equipment, but also repair and refurbishment will become difficult if the necessary refrigerant cannot be obtained. Many common refrigerants shall become in ever shorter supply: R410A; R407C; R134a. Pricing is already reflecting the Global Warming
Potential rating, with those higher GWP CO2 tonnage steadily rising above those with lower ratings.
So what to use next ?
Here lies a real and until now largely ignored, or at least certainly unanswered, problem depending upon which refrigerant is being considered. R407C and R410A are found in an awful lot of chillers, indeed substantial volumes of new chillers are even now being sold new using R410A. R134a will also be affected, but unlike R410A and R407C, R134a has established alternatives suitable for chiller applications.
R407C along with any other interim or direct replacement R22 characteristic refrigerants face a particular dilemma. Because no new equipment
28 August 2017
has been developed to use these refrigerants since ~ 2000, when R22 was banned in new use equipment, and R134a was established as more energy efficient, there is little incentive for gas manufacturers to develop refrigerants to resolve for a second time the phase out of R22 (characteristic) gases.
But R407C has been actively promoted in many many chillers right up until 2010 and beyond. With no replacement refrigerant offering a realistic direct replacement then users of R407C equipment are going to find they have no choice but to scramble for rapidly diminishing and increasingly expensive stocks of R407C. And the same scenario will affect the other blends created to replace R22 - R422D; R438A; R417A, etc. R410A remains the refrigerant of choice for VRF and smaller split type AC systems, but it does have a high GWP so it too must go, and sooner than R134a.
The mega manufacturers are developing smaller split systems to operate upon R32, the higher pressure component of R410A, which does have a low GWP rating, but here there is a significant safety issue brought about by the flammability of R32. Presently system capacity of the refrigerant fluid is governed by the indoor space into which the refrigerant could potentially leak - the smaller the space the less the volume it is safely permissible to leak.
This means if there is a room size minimum on single room split systems having a system charge weight maximum. Anywhere using a multi split / VRF style system with multiple indoor units will simply not be feasible, after all the principle is that the safety factor has to account for a complete system leaking into any one of the individual spaces being cooled. This may rule out R32 entirely as suitable for multi systems, but I understand the jury is still out on this one. It also seem unlikely R32 will be suited to water chillers unless these are specifically designed to
cope with the immense pressures. R410A does have some non HFC / low HFC blends in the offing, but all will have at least A2L flammability criteria that will have to be taken into account when risk assessing any particular installation.
R410A
It seems bizarre to be considering a retrofit on R410A systems that are still being openly sold to the market as new. It is likely R410A will simply not be available in the quantity required to supply the market within just five years. Bearing in mind the Market presently means new equipment and repair of existing equipment. The volume that can be imported or manufactured into the EU (and that will almost certainly include a post Brexit UK) is reducing in heavily policed stages.
Refrigerant manufacturers I have spoken to have stated that although there are blends under development and in field testing for R410A characteristic applications, all have at least A2L flammability and that this must be taken into account by the equipment designer. They are certainly not advocating use for retrofit. In this regard the refrigeration technician offering a quotation / proposal for undertaking a retrofit using one of these gases may find himself wearing the (re-)designers hat, and with that culpable responsibility to have undertaken an adequate risk assessment of the equipment he chooses to retrofit.
Personally I cannot see how systems with a base design completely ignoring A2L limitations can ever be regarded as Risk Assessment Low risk when applying a flammable gas which was never taken into account when the equipment was originally designed, although those used in open atmosphere or with no enclosed sub-systems it may be straight forward to accept as inherent low risk.
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