analyses of the r404a hot gas by‐pass at the … calculaon of the mass ﬂows and inlet ... 8...

AnalysesoftheR404ahotgasby‐passattheAccumulatorspiral

BartVerlaatNikhef/CERNDT

8October2010VL209

AC110

HT110

VL206

HX206

Hotgasby‐pass

AccuControl

TT101

TT110

PT110

6

7

8October2010 [email protected]

114.55kJ/kg 67.5kJ/kg

178kJ/kg 67.5kJ/kg

Withsubcooling(InternalHEX)Withoutsubcooling

Hotgasby‐passanalyses(Wheretogetthe840baseloadfrom?

HotgasinjecYoninAccuspiralinlet

R404a


MathcadcalculaYonofthemassflowsandinletcondiYonoftheaccumulatorspiral

MathcadcalculaYonoftherequiredhotgasinjecYonvalveCv



CalculaYngpressuredropandheattransferinthecoolingspiralwiththeWolverineEngineeringdatabookIIIcalculator

Hotgasby‐passvalveCv(‐)

Hotgasmassflow(g/s)

Liquidmassflow(g/s)

Totalmassflow(g/s)

Vaporqualityatinlet(‐)

Pressuredrop(bar)

Heattransfercoefficient(W/m2K)

AxialdT(duetodP)(°C)

RadialdT(DuetoHTC)(°C)

Maximumcoiltemp.(°C)

Nosubcooling

Hotgasby‐passonly(840W)

0.068 4.6 2.7 7.3 1 0.14 ‐ 1.6 ‐ ‐28.4

500Waccuand840WHotgasby‐pass

0.068 4.6 7.0 11.6 0.82 0.48 7268 5.2 0.6 ‐24.2

500WaccuandreducedHotgasby‐pass(340W)

0.027 1.9 5.4 7.3 0.68 0.21 4437 2.4 0.9 ‐26.7

20°CSub

coo

ling Hotgasby‐passonly

(840W)0.052 3.4 1.3 4.7 1 0.06 ‐ 0.7 ‐ ‐29.3


0.052 3.4 4.1 7.5 0.87 0.19 3959 2.2 1.0 ‐26.8


0.021 1.4 3.3 4.7 0.67 0.09 1770 1.0 2.3 ‐26.7

Resultsfora5mlong3/8”coil

Nosubcooling:Tcondenser=30°C,Tevaporator=‐30°C,Tliquid=30°C,Tcoldgas=‐20°C,Tdischarge=70°C

Withsubcooling:Tcondenser=30°C,Tevaporator=‐30°C,Tliquid=10°C,Tcoldgas=20°C,Tdischarge=100°C



Hotgasmassflow(g/s)

Liquidmassflow(g/s)

Totalmassflow(g/s)


Pressuredrop(bar)





Nosubcooling


0.068 4.6 2.7 7.3 1 0.27 ‐ 3.1 ‐ ‐26.9


0.068 4.6 7.0 11.6 0.82 0.96 7258 9.7 0.3 ‐20.0


0.027 1.9 5.4 7.3 0.68 0.42 4444 4.6 0.5 ‐24.9

20°CSub

coo


(840W)0.052 3.4 1.3 4.7 1 0.13 ‐ 1.4 ‐ ‐28.6


0.052 3.4 4.1 7.5 0.87 0.38 3938 4.2 0.5 ‐25.3


0.021 1.4 3.3 4.7 0.67 0.17 1761 2.0 1.2 ‐26.9

Resultsfora10mlong3/8”coil(LikeVTCSaccumulator)




Preliminaryconclusions

Hotgasbypassvalve.ValveCvvaluesarerangingfrom0.021to0.068UnfortunatelytheCVvaluesfortheselectedDanfoss/SaginomiyaKVexpansionvalvesarenotlisted.TosizethevalveacomparisonwiththeDanfossAKV‐10expansionvalveismadewhichhascoolingpowerandCvlisted.

TheAKV10‐5showacoolingpowerforR404aof4.9kW.ThenearestvalveintheKVexpansionseriesistheUKV‐18D02.TheexpansionvalveforthecoolinginjecYonwillbeUKV‐10D85.

AccumulatorspiralandcontrolThespiralintheaccumulatorcanbea3/8”5mlongtube.Thisissufficienttoremovethe500wahfromtheaccumulatorincludingthehotgasbypass.Thereducedhotgascontrolseemtobethemostpromising.ForthecontrolthismeansthatfirstthehotgasvalveisclosedbeforetheliquidinjecYonisincreased.


114.55kJ/kg 67.5kJ/kg

178kJ/kg 67.5kJ/kg

Withsubcooling(InternalHEX)Withoutsubcooling

Hotgasby‐passanalyses(Wheretogetthe840baseloadfrom?

HotgasinjecYoninAccumulatorspiralinlet

R404a


CalculaYonofthemassflowsandinletcondiYonoftheaccuspiral

CalculaYonoftherequiredhotgasinjecYonvalveCv



Hotgasmassflow(g/s)

Liquidmassflow(g/s)

Totalmassflow(g/s)


Pressuredrop(bar)





Nosubcooling


0.068 4.6 2.7 7.3 1 0.14 ‐ 1.6 ‐ ‐28.4


0.068 4.6 7.0 11.6 0.82 0.48 7268 5.2 0.6 ‐24.2


0.027 1.9 5.4 7.3 0.68 0.21 4437 2.4 0.9 ‐26.7

20°CSub

coo


(840W)0.052 3.4 1.3 4.7 1 0.06 ‐ 0.7 ‐ ‐29.3


0.052 3.4 4.1 7.5 0.87 0.19 3959 2.2 1.0 ‐26.8


0.021 1.4 3.3 4.7 0.67 0.09 1770 1.0 2.3 ‐26.7

Resultsfora5mlong3/8”coil





Hotgasmassflow(g/s)

Liquidmassflow(g/s)

Totalmassflow(g/s)


Pressuredrop(bar)





Nosubcooling


0.068 4.6 2.7 7.3 1 0.27 ‐ 3.1 ‐ ‐26.9


0.068 4.6 7.0 11.6 0.82 0.96 7258 9.7 0.3 ‐20.0


0.027 1.9 5.4 7.3 0.68 0.42 4444 4.6 0.5 ‐24.9

20°CSub

coo


(840W)0.052 3.4 1.3 4.7 1 0.13 ‐ 1.4 ‐ ‐28.6


0.052 3.4 4.1 7.5 0.87 0.38 3938 4.2 0.5 ‐25.3


0.021 1.4 3.3 4.7 0.67 0.17 1761 2.0 1.2 ‐26.9

Resultsfora10mlong3/8”coil(LikeVTCSaccu)




Conclusions

Hotgasbypassvalve.ValveCvvaluesarerangingfrom0.021to0.068UnfortunatelytheCVvaluesfortheselectedDanfoss/SaginomiyaKVexpansionvalvesarenotlisted.TosizethevalveacomparisonwiththeDanfossAKV‐10expansionvalveismadewhichhascoolingpowerandCvlisted.

TheAKV10‐5showacoolingpowerforR404aof4.9kW.ThenearestvalveintheKVexpansionseriesistheUKV‐18D02.TheexpansionvalveforthecoolinginjecYonwillbeUKV‐10D85.

AccumulatorspiralandcontrolThespiralintheaccumulatorcanbea3/8”5mlongtube.Thisissufficienttoremovethe500wahfromtheaccumulatorincludingthehotgasbypass.Thereducedhotgascontrolseemtobethemostpromising.ForthecontrolthismeansthatfirstthehotgasvalveisclosedbeforetheliquidinjecYonisincreased.


analyses of the r404a hot gas by‐pass at the … calculaon of the mass ﬂows and inlet ... 8...

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