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THE ANALYSIS AND EXPERIMENTAL INVESTIGATION OF HEAT PUMP SYSTEM OF R404A AND R410A USING

THERMOBANK AND A TWO-PHASE EJECTOR

DEPT. OF REFRIGERATION AND AIR CONDITIONING ENGINEERING, CHONNAM NATIONAL UNIVERSITY, SOUTH KOREA.

Jong-Taek Oh*

Le Ngoc Cuong, Kwang-Il Choi

12th IEA Heat Pump Conference

Thermal & Refrigeration Engineering Lab

CHONNAM NATIONAL UNIVERSITYIEA 2017

Background Apparatus Result & Discussion Conclusions

Contents

1

2

3

4

Experimental Model

Background

Results and Discussions

Conclusions



Background

1

2The thermobank was used in refrigeration cycle fordeveloping of a refrigerated vehicle for sliced-raw fishtransportation; a faster defrost and decrease load.

4

The ejector and thermobank are used in refrigerationsystem to increase the COP and decrease thecompressor displacement.

Result & Discussion Conclusions

The objective of this study is to develop high performance heat pump system using thermobankand ejector and R410A/R404A.

Apparatus

3 Preservation of agricultural products in cold storage and heating of floor panel to warm the room in rural house using heat pump system.



Experimental Facilities and Method

v

COMPRESSOR

SIGHT GLASSRECEIVER

CONDENSER

5DRY FILTER

EVAPORATOR

I/V

EXP. VALVETICT3

TEV

3 4

2

1

6

7 THERMOBANK

(FOR COLD STORAGE)

3WAY VALVE

s

FOR DEFROST

FOR DEFROST

FOR COOLING

FOR COOLING

COLD STORAGE

ROOM HEATING

8

9WATER PUMP

s

3WAY VALVE



Apparatus

1.Experimental Model

Background Result & Discussion Conclusions



Apparatus

3. P-h diagram


Qe



Apparatus

2. Ejector schematic




ApparatusBackground Result & Discussion Conclusions

4. Energy balance equations in the primary and secondary nozzle section

𝒉𝟓 = 𝒉𝟕 +𝑽𝟕𝟐

𝟐

𝜼𝒊𝒔(𝟓-𝟕) = 𝒉𝟓 − 𝒉𝟕

𝒉𝟓 − 𝒉 𝒑𝟕, 𝒔𝟓

𝒉𝟏𝟐 = 𝒉𝟔 +𝑽𝟔𝟐

𝟐

𝜼𝒊𝒔(𝟏𝟐-𝟔) = 𝒉𝟏𝟐 − 𝒉𝟔

𝒉𝟏𝟐 − 𝒉 𝒑𝟔, 𝒔𝟏𝟐




5. Mass equations in term of entrainment ratio (U)

𝑼 = �̇�𝟔�̇�𝟕7

𝝆𝟕𝑨𝟕𝑽𝟕 = �̇�𝟕 = 𝟏/(𝟏 + 𝑼)

𝝆𝟔𝑨𝟔𝑽𝟔 = �̇�𝟔 = 𝑼/(𝟏 + 𝑼)




6. Momentum, energy and mass equations in the mixing section

𝝆𝟕𝑨𝟕𝑽𝟕 +𝝆𝟔𝑨𝟔𝑽𝟔 = 𝝆𝟖𝑨𝟖𝑽𝟖

𝝆𝟕𝑨𝟕 +𝟏

𝟏 + 𝑼𝑽𝟕 +𝝆𝟔 𝑨𝟔 +𝑼

𝟏 + 𝑼𝑽𝟔

= 𝝆𝟖𝑨𝟖 +𝑽𝟖 + 𝚫𝒑𝒇𝑨𝟖

𝟏𝟏 + 𝑼 𝒉𝟕 +

𝑽𝟕𝟐

𝟐 +𝑼

𝟏 + 𝑼 𝒉𝟔 +𝑽𝟔𝟐

𝟐

= 𝒉𝟖 +𝑽𝟖𝟐

𝟐

𝑨𝟖 = 𝑨𝟕 + 𝑨𝟔




7. The energy balance in the diffuser section

𝒉𝟗 = 𝒉𝟖 +𝑽𝟖𝟐

𝟐

𝜼𝒊𝒔(𝟖-𝟗) = 𝒉 𝒑𝟕, 𝒔𝟓 − 𝒉𝟖

𝒉𝟗 − 𝒉𝟖

8. Ejector outlet pressure

𝑷𝟗 = 𝑷𝟖 + 𝟐𝑮𝑽𝟖(𝑨𝟗𝑨𝟖

− 𝟏)-𝟏




9. The overall energy balance and efficiency in the ejector

10. The COP

𝟏𝟏 + 𝑼𝒉𝟓 +

𝑼𝟏 + 𝑼𝒉𝟏𝟐 = 𝒉𝟗

𝜼𝒆 = �̇�𝟕 + �̇�𝟔 𝚫𝒉𝒄 − �̇�𝟔𝑽𝟔𝟐/𝟐

�̇�𝟕(𝒉𝟓 − 𝒉𝟕)

= 𝟏 + 𝑼 𝚫𝒉𝒄 − 𝑼𝑽𝟔𝟐/𝟐

(𝒉𝟓 − 𝒉𝟕)

𝑪𝑶𝑷 = 𝑼𝒉𝟏𝟐 − 𝒉𝟏𝟏𝒉𝟐 − 𝒉𝟏




11. Compressor specification

Compressor Seltec TM-15HD

Cylinder 6

Nominal 2000 rpm

Displacement 147 cm3

Refrigerants R404A, R410A




12. Condenser specification

Condenser Aluminum finned

Rows 4

Diameter cooper tube 9.53mm

Total area 13.635 m2

Frontal area 0.2 m2

Fan 2×250 mm diameter, 80w, 12/24V, 1400m3/hr




13. Evaporator specification

Evaporator Aluminum finned

Rows 6

Diameter aluminum tube 9.53mm

Total area 8.52 m2

Frontal area 0.172 m2

Fan 2×250 mm diameter, 80w, 12/24V, 1400m3/hr

Expansion valve FSE-1/2-C




14. Ejector specification

Ejector 180 mm length

Diameter nozzle 1 mm

Diameter mixing 6 mm

Diameter diffuser 16 mm




15. Thermobank specification

Thermobank 600×300×400mm

Rows 2


Circuits 4

Mass of water 50 kg

Tin (water) 200 C




16. Heating panel specification

Heating panel 800×150×300mm

Rows 2


Circuits 12

Mass flow rate of water 1.5 m3/hr

Total area 14 m2



Result & Discussion

1. Water temperature in Thermobank

Background ConclusionsApparatus

Contour of water temperature in thermobank Vin water = 0.25(m/s)


R404A R410A



Apparatus

Saturation refrigerant properties


Refrigerant Tsat(℃)

P(Bar)

ρf(kg/m3)

ρg(kg/m3) ρf/ρg

μf(10-6Pas)

μg(10-6Pas) μf/μg

R-404A

44 20 855.14 116.01 7.37 107.86 14.48 7.45

-20 2.96 1221.80 15.409 79.291 231.95 10.55 21.99

-10 4.39 1186.9 21.905 54.18 202.67 10.99 18.44

R-410A

33 20 1016.4 83.703 12.14 111.88 14.16 7.90

-20 4 1245.1 15.415 80.77 211.46 10.09 20.96

-10 5.75 1208.7 21.942 55.086 187.44 11.45 16.37



Result & Discussion

1. Water temperature in Thermobank




R404A R404A



Result & Discussion

2. Refrigerant temperature in Thermobank


Contour of inlet temperature of vapor refrigerant (thermobank)

Contour of inlet temperature of refrigerant (thermobank)

R404A R410A



Result & Discussion

2. Refrigerant temperature in Thermobank


Contour of outlet temperature of vapor refrigerant (thermobank)

Contour of outlet temperature of refrigerant (thermobank)

R404A R410A



Result & Discussion

5. Velocity of refrigerant in ejector


Contour of velocity (m/s)

R404A



Result & Discussion

5. Velocity of refrigerant in ejector


Contour of velocity (m/s)

U = 0.3



Apparatus

Saturation refrigerant properties


Refrigerant Tsat(℃)

P(Bar)

ρf(kg/m3)

ρg(kg/m3) ρf/ρg

μf(10-6Pas)

μg(10-6Pas) μf/μg

R-404A

44 20 855.14 116.01 7.37 107.86 14.48 7.45

-20 2.96 1221.80 15.409 79.291 231.95 10.55 21.99

-10 4.39 1186.9 21.905 54.18 202.67 10.99 18.44

R-410A

33 20 1016.4 83.703 12.14 111.88 14.16 7.90

-20 4 1245.1 15.415 80.77 211.46 10.09 20.96

-10 5.75 1208.7 21.942 55.086 187.44 11.45 16.37



Result & Discussion

6. Water temperature in thermbank (pump off)


R404A



Result & Discussion

6. Water temperature in thermbank (pump off)


R410A



Result & Discussion

7. Water temperature in thermbank


Pump On

R404A



Result & Discussion

8.The effect of mixing dimension to ejector outlet pressure


Dnt =1mm, Dd =16mm



Dnt =1mm, Dm =6mm

Result & Discussion

9.The effect of diffuser dimension to ejector outlet pressure




Result & Discussion

10. The effect of entrainment ratio to COP




Result & Discussion

11. The COP comparison of standard and improved cycle




Conclusions

1

2

3

Heat pump system using thermobank and ejector has beendeveloped by CFD simulation and experimental investigation.

Using Ejector and Thermobank can save energy for heat pumpsystems, COP increases up to 38.5% (R404A) and 42.7%(R410A) .

This heat pump system can be used to keep preservation ofseafood in cold storage and floor heating panel to warm thelunar house in winter.

Background Result & DiscussionApparatus

4

The specifications of the ejector are optimized for the heatpump system using thermobank and ejector.

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