Sponsored by REFRIGERANTS Making an
R1234ze difference H
A-Gas refrigerant product manager Roger Smith explains why R1234ze is a viable alternative to R134a in chiller applications
FO R1234ze is a sustainable, energy-efficient option for different medium temperature uses and has been selected by a number of equipment manufacturers for applications with a capacity range from several kW to 20MW and with large variations in charges.
10
Its use includes installations involving large chiller applications and sizeable commercial air conditioning systems in supermarkets and commercial buildings. R1234ze has also been employed to handle medium- temperature jobs featuring heat pumps and CO2
cascade systems in commercial refrigeration.
You should bear in mind that as an HFO it does not fall as yet under the remit of the current F-Gas Regulations’ phasedowns which gives it a lengthy commercial life and in turn enhances its green credentials.
In the right circumstances R1234ze is a very handy refrigerant because it is such an excellent alternative to the widely-used HFC R134a. Making a direct comparison with R134a when used in a large chiller application is a practical way of highlighting the effectiveness of R1234ze. Firstly, the GWP and operating pressure figures make encouraging reading. Apart from the GWP dropping from a sizeable 1320 to seven, in a typical application allowing for a system with an evaporating temperature of 4°C and a condensing temperature of 40°C, your operating pressure is reduced by from 2.36 bar to 1.49 bar.
This is important as it has a significant effect on the running of the equipment because by lessening the pressure you will reduce the potential for leakage. Driving down leakage rates
is a key element of managing refrigerant use under the F-Gas Regulations.
It is worth putting a lot of effort into doing so if you want to achieve F-Gas best practice but if you can prevent the horse escaping through the stable door in the first place, so much the better and R1234ze can play a role in this. In our example the other good news is that the compressor discharge temperature will also be reduced by around 6°C and this means there is less work for the condenser and in turn less strain on the compressor. Looking after the compressor is a key element in the welfare of any system. The good work of this unsung hero in a cooling system can be widely under estimated, so steps to lessen the workload do reap dividends. One of the biggest positives from opting for R1234ze is a reduction in the condensing pressure which in my example will drop from 9.1 to 6.6 bar. Other positives in relation to this mean that you will once again reduce the potential for leakages and this may also allow you to use lighter gauge tubing. I have established that R1234ze saves the compressor a lot of grief by reducing wear and tear, has lower discharge temperatures and drives down operating temperatures but another key benefit is that this gas makes the system more energy efficient.
You can save around 1% on energy use, which does not seem a lot in the first instance, but when this involves a large chiller system running day in and day out, that’s a sizeable amount of money the end user won’t have to spend on power over a year. If you focus on the refrigerant charge, and for example you have 80kgs of R134a in a system, you will need less R1234ze to
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 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120
