BY SHASHANK. S. SURVE TEJAS. N. PAWAR

CONTENTS  INTRODUCTION:-  ABOUT HFO -1234yf.  STRUCTURAL FORMULA.  NEED OF HFO-1234yf.  WHY NOT R-134a SHOULD BE USED.  THERMODYNAMIC PROPERTIES OF HFO.  COMPARISONS OF VARIOUS PROPERTIES OF HFO AND PREVIOUSLY USED REFRIGERANTS.  MERITS  DEMERITS

INTRODUCTION  HFO-1234yf is introduced by Honeywell and DuPont  HFO-1234yf is a type of fluorocarbon with some advancements(discussed further).  Honeywell undertook several tests on toxicity of this fluorocarbon for e.g. cardiac sensitization, genetic testing, genomic testing or reproductive testing. Results were clear that there is no negative influence on human health.  It has zero ozone layer depletion potential.  The Global Warming Potential of these refrigerant is 4.

STRUCTURAL FORMULA  The chemical name for HFO-1234yf is 2,3,3,3-Tetrafluropropene.  DuPont And Honeywell Have Identified HFO-1234yf as CF 3 CF=CH 2.  The name HFO-1234yf is given on the basis of designation of Refrigerants.  WHY THE NAME IS SO?

STUCTURAL FORMULA

NEED OF HFO-1234yf  CO 2 was used as the refrigerant earlier.  R-134a then came into existence due to its low environment harming potential.  But due to the GWP of R-134a being 100 it needed to be replaced.  Thus from 1 January 2011 onwards the European Nations decided to use HFO-1234yf as a refrigerant due to its higher energy efficiency and improved Life Cycle Climate Performance.

Why not R134A?  The 100 year GWP for R134A is 1300  Governments are looking for all the ways to reduce greenhouse gasses and global warming

Why not R134A?  By 2016 the EPA is requiring a corporate fleet average of less than 250 g/mile of CO2 requirement  A lower GWP refrigerant equals emissions credit for the manufacturer’s fleet

THERMODYNAMIC PROPERTIES  Vapor pressure and critical pressure :  The vapor pressure was calculated using batch- type calorimeter between the temperature ranges from 310k to 360k.  The experimental uncertainties observed were estimated to be within 1kpa.  The critical pressure was determined to be 3382+or-3kpa by using the extrapolation method.

 Critical Temperature :  The critical temperature measurement was done by collecting the twenty two data points for the saturated vapour for HFO-1234yf near the critical point.  The experimental uncertainties of the temperature measurement are estimated to be within 5mk.  On the basis of the experiment the critical temperature was observed to be or k.

 Minimum Ignition Energy:  The experiment was conducted to calculate the minimum ignition energy of three refrigerants i.e. HFC-32, Ammonia and HFO-1234yf.  The results obtained were as follows:-  From this it is clear that it is very difficult to ignite HFO-1234yf with electric spark. Thus its flammability is mild. RefrigerantIgnition Occurred at ntp Ignition occurred at stp HFC /- 12 mJ100 +/- 30 mJ Ammonia 100 +/- 30 mJ300 +/- 100 mJ HFO-1234yf 5,000 +/- 350 mJ10,000 +/- 350 mJ

Fundamental constants of HFO-1234yf Property SymbolValue Molar massM g/mol Critical temperatureTcTc K Critical pressurePcPc 3.382MPa Critical density ƤcƤc 478kg/m 3 Acentric factor ώ 0.280

COMPARISONS OF VARIOUS PROPERTIES OF HFO AND PREVIOUSLY USED REFRIGERANTS :  The annual ecoharmful gas emission graph of various refrigerants

PropertiesHFO-1234yfR-134a p vap MPa (25 0 c) P vap MPa(80 0 c) GWP (100 ITH)41410 toxicitylow flammabilitymildnone Some basic comparisons over R-134a

P-T GRAPH FOR R134a & HFO- 1234yf

MERITS  Excellent environmental properties.  Very low GWP.  Low toxicity, similar to R-134a.  Favourable Life Cycle Climate Performance.  Low acute and chronic toxicity.  System performance very similar to R-134a.  Excellent COP and Capacity  Thermally stable and compatible with R-134a components

DEMERITS There are only two demerits of HFO-1234yf that are:  Mild Flammability  Slight modification in the refrigeration structure.

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