Past Activity

Thermo-fluid dynamic analysis of industrial refrigerating machines/COMHETA facility

Activity description
Experimental facility - (Facility Performance )
Applications

Activity responsible: Dr. Gino BOCCARDI
Address: ENEA C.R. Casaccia, Energy Department, Institute of Thermal Fluid Dynamics, Via Anguillarese 301 (S.P. 092), 00060 S. M. di Galeria RM, Italy
Phone: +39 06 3048.3664 Fax: +39 06 3048.3026

Email: boccardi@casaccia.enea.it


Activity description

The research purpose is to test the influence of some thermal-hydraulic
parameters on the global overall heat transfer coefficient. R134a, R407C,
R410A, and R22 are the fluids tested under reference thermal conditions.
Also, a new method for calculating the thermodynamical mixture parameters,
presented in Boccardi et al. (1998), is applied to the phase change of mixtures
R407C and R410A and its benefit evaluated. The refrigerant loop overall performance
and the condenser and evaporator global heat transfer coefficients are the
parameters chosen to enlighten the characteristics of the alternative refrigerants
(R134a, R407C, and R410A) with respect to the fluid that they are supposed
to substitute (R22).

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Experimental facility

Click here to see the complete scheme of the facility.

The test facility consists of three closed cycle loops: a refrigerant cycle, a water loop for the evaporator and another water loop for the condenser.

The refrigerant flow is regulated by a reciprocating compressor that can work at 33%, 66% or 100% of its displacement, and an inverter that allows a variation in the frequency of the power supply between 30 and 60 Hz. There are different thermostatic valves for each fluid and flow rate to control the DTsup at the inlet of the compressor..

An electric boiler in the evaporator water loop supplies the thermal load and allows the control of the inlet and outlet water temperatures of the exchanger; the water flow rate is controlled by a regulation valve.

The test conditions on the water side of the condenser are obtained by:

  • two three-way valves, that deliver a part of the flow to the two shell and tube heat exchangers connected with a cooling tower circuit;
  • an electric heater that allows a precise regulation of the inlet and outlet temperatures of the condenser;
  • two centrifugal pumps and two regulation valves.

A mass flow meter is installed in the refrigerant loop; the flow rates in the other loops are measured by volumetric flow meters. The temperature and pressure values are measured at the inlet and outlet of all the main components of the facility.

Facility performance

   

Condenser loop

Refrigerant loop

Evaporator loop

Fluid

 

water

R134a, R22, R407C, R410A

water

Mass flow rate (min/max)

kg/s

3 / 8

-

1.4 / 5.3

Compressor volumetric flow rate (50/60 Hz)

m3/h

-

126.7 / 152.4

-

Temperature (min/max)

°C

10 / 90

-5 / 130

2/90

Pressure (min/max)

bar

2 / 10

1 / 25

1 / 5

Heater electric power . (max)

kW

250

-

150

 

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Applications

1 st Test Campaign

Results obtained so far are reported in:

EFFICIENZA TERMICA DI SCAMBIATORI DI CALORE COMPATTI IN BIFASE CON FLUIDI REFRIGERANTI DELLA NUOVA GENERAZIONE
G.Boccardi, E. Brignone, G.P. Celata, M. Cumo
ATTI 52° CONGRESSO ATI, Settembre 1997, Cernobbio (CO) 

Boccardi, G. and Celata, G.P. and Cumo, M. and Gerosa, A. and Giuliani, A. and Zorzin, A. 1998. The Use of New Refrigerants in Compact Exchangers for the Refrigeration Industry, Proceedings of the International Conference and Exhibit on Heat Exchangers for Sustainable Development, pp. 293-301, Lisbon.
Heat Transfer  Engeneering Journal Vol. 21 n.4, July-August 2000

Boccardi, G. and Celata, G.P. and Cumo, M. and Gerosa, A. and Giuliani, A. and Zorzin, A. 1998. Alternative Refrigerant Performance in Plate Heat Exchangers for Air Conditioning, Proceedings of the Eurotherm Seminary n° 62 HEAT TRANSFER IN CONDENSATION AND EVAPORATION , pp. 554-562, November 1998, Grenoble (France) .
Pubblicato su International Journal of Heat & Tecnology ...

ALTERNATIVE REFRIGERANT PERFORMANCE IN PLATE HEAT CONDENSERS FOR AIR CONDITIONING
G.Boccardi, G.P. Celata, M. Cumo, a. Gerosa, D. F. Marchesi, A. Zorzin
Proceedings of International Conference on COMPACT HEAT EXCHANGERS AND ENHANCEMENT TECNOLOGY FOR PROCESS INDUSTRIES , pp. 431-438
July 1999, Banff  (Canada)

SCAMBIATORI COMPATTI PER IL CONDIZIONAMENTO AMBIENTALE
G.Boccardi, G.P. Celata, M. Cumo, A. Gerosa, F. Marchesi, A. Zorzin
La Termotecnica n.10, Dicembre 1999

SVILUPPO DEGLI SCAMBIATORI DI CALORE COMPATTI PER IL CONDIZIONAMENTO AMBIENTALE
G.Boccardi, G.P. Celata
Nota Tecnica – ENERGIA AMBIENTE INNOVAZIONE - N°1, 2000

R22 REPLACEMENT ASPECTS IN COMPACT HEAT EXCHANGERS FOR AIR CONDITIONING
G.Boccardi, G.P. Celata, M. Cumo, A. Gerosa, F. Marchesi, A. Zorzin
International Journal of Heat Exchangers, Vol.1, pp77-92, 2000

ALTERNATIVE REFRIGERANTS PERFORMANCE IN EVAPORATORS OF PLATE EXCHANGERS TYPE
Gino Boccardi, G.P Celata - ENEA – Rome
Proceedings of 3rd International Conference on COMPACT HEAT EXCHANGERS AND ENHANCEMENT TECNOLOGY FOR PROCESS INDUSTRIES
1-6 July 2001 Davos  (Switerland)

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1st Campaign

The first work program included tests on three new fluids and R22 as a reference, using two pairs of evaporators and condensers of different thermal power and designed to work with R22. In particular, the performance of evaporators is evaluated by changing the main thermal-hydraulic inlet parameters.

The test matrix used for testing evaporators involves the control of the following parameters:

  • inlet water temperature (12°C);
  • outlet water temperature (7°C);
  • condensation temperature (40°C);
  • D T superheating (outlet evaporator) (5-7 K);
  • D T subcooling (outlet condenser) (3-5 K).


Table I shows the working ranges of the other main parameters of the refrigeration circuit observed during the tests.

Table I : Test conditions

Fluid

Evap.
type

S


plate

Wr

xi
Evap.

Tsat

Gw

Gr



m2


kW

%

°C

kg/s

kg/s





min/max
min/max
min/max
min/max
min/max

R134a

A

7.41

80 57.3/67.4

15.5/21.0

2.9/3.9

2.7/3.2

0.36/0.40

"
B

3.9

80

37.9/55.8

22.5/25.5
0.3/3.6
1.8/2.7
0.2/0.31

R407C

A
7.41
80

57.0/96.4

19.0/21.5

4.5/5.5

2.72/4.61

0.31/0.56

"
B

3.9

80

37.9/55.8

22.5/25.5

0.3/3.6

1.79/2.67

0.20/0.31

R410A

A
7.41
80

66.3/105.8

22.2/25.3

2.6/4.0

3.41/5.08

0.39/0.62

"
B

3.9

80

32.5 /54.5

23.8/27.5

0.9/3.4

1.60/2.71

0.19/0.32

R22

A
7.41
80

64.9/101.9

17.7/0.3

-0.3/0.8

3.13/4.71

0.39/0.59

"
B
3.9
80

40.1/58.2

20.6/22.2

-1.4/1.1

1.82/2.66

0.24/0.35


Moreover, a New Thermodynamical Method was applied with the purpose of defining the saturation temperature and investigating the other main parameters of zeotropic mixtures in the two phase region for the fluids R407C and R410A, that are blends of, respectively, three and two pure refrigerants.

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