Product Developments 27
alternative for R134a having a close performance match across the range of application operating conditions. With a glide comparable to R407C, AC5X is suited to direct expansion (DX) evaporator systems.
BRB36 – with a glide of less than 0.5K and a GWP of around 500, this non- flammable blend of R1234ze and R134a, is intended as an alternative to R134a particularly in flooded evaporator systems albeit with a reduced capacity relative to R134a or AC5X.
Other stationary sector Fluids In addition to R134a alternatives, industry is also looking to develop alternatives for the R404A and R410A application sectors. Mexichem’s developmental refrigerants for these sectors include: LTR4X – a non-flammable blend of R32, R125,R134a and R1234ze. With a GWP of 1300, this fluid is intended as a non- flammable alternative for R22, R407A or R404A in DX applications.
HPR2A – a blend of R32, R134a and R1234ze with a GWP of around 600. With a reduced compressor discharge temperature relative to R32 and potentially weaker overall flammability, HPR2A is targeted at R410A DX systems.
HPR1D – as HPR2A, an alternative to R410A for some DX applications with a GWP of 400 and weaker overall flammability than R32.
Refrigerant performance
One measure of carbon footprint in use is the Life-Cycle Carbon Production (LCCP). Using data from the CRP MRB, the LCCP of the automotive alternatives can be quantified across a range of geographic environmental conditions, and the three low-GWP alternative fluids (R444A, R445A and R1234yf) all have potential to deliver tangible reduction in LCCP compared to R134a.
Compressor calorimetry testing of AC5X on a number of commercial reciprocating and scroll compressors typically used in supermarket refrigeration shows a very good match in performance to R134a across the range of evaporation and condensing conditions.
While BRB36 has a capacity reduction relative to R134a, typically around 10% across a range of operating conditions, the system efficiency is almost identical to R134a.
While R1234ze is also similar in efficiency to R134a, it has a significantly greater capacity reduction, of the order of 25% or so, and is mildly flammable (2L). On this basis, BRB36 offers an attractive combination of low GWP, non-flammability and closer performance match to R134a.
Toxicology
The toxicology of R1234ze has been investigated and is documented as part of its ASHRAE classification.
The accepted chronic exposure limit (OEL) of 800ppm is similar to that of R134a as is its acute exposure limit. The formulated refrigerants developed by Mexichem are all expected to have OEL above 500ppm and hence to be classified as ‘A’ by the ASHRAE-34 methodology.
Summary
By careful design and taking into account the range of application requirements it is possible to develop fluids having a reduced environmental footprint in comparison to many of the HFC refrigerants used today.
These fluids have reduced GWP, good energy efficiency and broad compatibility with existing system designs. While some of the alternatives are flammable, their 2L rating provides greater margins of safety than can be achieved with other low GWP alternatives such as R152a or hydrocarbons.
Nevertheless, there is still some way to go before the benefits of 2L are fully recognised and incorporated into industry codes.
A combination of good thermodynamic properties, the potential for favourable production costs and significant installed production capacity make R1234ze an attractive material on which to base a range of refrigerant blends to address the needs of a variety of application end uses.
Armacell
Visit ACR News online at
www.acr-news.com
ACR News May 2014
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68