Working fluid for energy efficiency 2016 CTP CoqueletFor Energy Efficiency
Directeur CTP
Mines ParisTech, PSL – Research University, CTP - Cen tre Thermodynamique des Procédés, 35 rue St Honor é, 77305 Fontainebleau Cedex, France
Centre of Thermodynamics of ProcédésChristophe.coquelet@mines-paristech.fr
MOTIVATIONS
New regulations concerning utilisation of fluids (F-gas) Several candidates for various applications: refrigeration, heat
pumps, climatisation, ORC, etc.. Numerous fluids (pure component or mixture) can be used Necessity to use predictive tools in order to select the best
candidates for each applications (Refrigeration, heat pump, ORC, etc..) Thermodynamic: Predictive equations of state have to be developed considering group contribution or corresponding state approach Transport properties: Correlations or models like SUPERTRAPP can be used to estimate thermal conductivity, viscosity for example
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ρvD e=
P λ
µCp r =
3
The specific objectives are as follows:
•To identify the gaps in available literature on the phase behaviour (VLE, bubble pressure, critical point, heat capacity) and fluid properties (thermal conductivity, viscosity and density...) for working fluids: creation of a database •To perform phase behaviour measurements for binary systems and for representative multicomponent systems. •To provide real information concerning the energy efficiency of working fluids (experiments and simulations). •To evaluate the viscosity and density over a wide range of pressure and temperature conditions. •To develop molecular simulation models (force field) in order to generate thermophysical properties of new generation of working fluids (pure component and mixtures) •To develop predictive equation of state with or without molecular based •To develop/tune predictive tools to predict the phase behaviour, transport properties, for working fluids •Interfacial tension
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JIP or Industrial Chaire
The suggested topics are: • Development of database with compilation of data relevant to the project. • Critical evaluation of existing data • Molecular simulation work
– Development of force field – Monte Carlo and molecular dynamics simulations
• Phase behaviour : VLE, bubble pressure, critical point properties • Volumetric properties for temperature lower or higher than critical temperature • Calorimetric and thermal properties (thermal conductivity) • Viscosity • Interfacial tension • Development of predictive equations of state • Evaluation of the working fluids considering process simulation aspects and test
on real machine • Water content to avoid frost point • Compatibility with lubricant
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MOTIVATIONS Example of work done for Edf Chatou (Fluid selection) – Franck David
• The selection of the fluids is mainly based on their energetic performances evaluated on energetic machines.
• The performance (COP) is generally evaluated from a process simulator and confirmed after several tests on existing machines.
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Collaboration CES- CTP-PERSEE
MOTIVATIONS Predictive equations of state
• Objectives
Knowledge of phase diagram is essential (azeotrope, critical point, relative volatility, conditions of apparition of liquid liquid equilibrium, solubility in lubricant
• Density predictions
Estimation of the densities of both vapor and liquid phasse with the maximimum of accuracy
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MOTIVATIONS Parameterization of equations of state
• Necessity of utilization of predictive EoS
– Group contribution approach – binary interaction parameter is calculated considering Group contribution
method. – Necessity of experimental works
• Possibility to consider molecular simulation calculation
– Monte Carlo approach for phase diagram and density predictions – Fluid dynamic to have the prediction of transport properties – Validation of potential of interaction by comparison with experimental data
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Molecular Simulation
Monte Carlo methods → Phase equilibrium properties for pure fluids and mixtures (densities, vapor pressures, Pxy diagrams…)
Molecular dynamics methods → Transport properties (viscosities, thermal conductivities…)
Necessity to represent the potential of interaction (force field) between the molecules using sevral methods like United Atom, Trapp, AMBER, etc..
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Equilibrium
Molecular Simulation
– Comparison of results with with Refprop 9.0
Development of Force Field concerning the new gener ation of refrigerant (HFO)
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240
260
280
300
320
340
360
critical point, density
Synthetic and analytic methods
Measurements of T, P, V and compositions for equilibrium properties
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• Static analytic method
• Phase sampling (ROLSI(TM))
• Gas Chromatography for the determination of the composition of each phase
• Determination of experimental uncertainty using NIST standard
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EC
ST
GC
TR
SD
V1
C2
V6
VP
PP
TP
TR
V5
EC: equilibrium cell; LV: loading valve; PP: platin um resistance thermometer probe; PT: pressure transducer; C1: mor e volatile compound; C2: less volatile compound; GC: gas chrom atograph; LS: liquid sampler; VS: vapor sampler; SC: sample c ontrolling; PC: personal computer; VP: vacuum pump.
Experimental Approach Vapor Liquid Equilibrium measurement
• Static analytic method
• Phase sampling (ROLSI(TM))
• Gas Chromatography for the determination of the composition of each phase
• Determination of experimental uncertainty using NIST standard
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• Static analytic method
• Phase sampling (ROLSI(TM))
• Gas Chromatography for the determination of the composition of each phase
• Determination of experimental uncertainty using NIST standard
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Experimental Approach Critical point measurement
Critical points were determined by observing the cr itical opalescence (dynamic method):
1) A mixture of known overall composition is prepared and sen t in the cell 2) The temperature is increased and the flow rate is regulate d in order to
maintain the meniscus in the middle of the cell 3) At the critical point, the cell becomes orange and the meni scus disappears
from the middle of the cell. T C and PC are recorded. 16
PSPS
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• Vibrating tube densimeter
• The measurements are based on the indirect synthetic method. The method is based on the relation between the vibrating period of a dimensional resonator and its vibrating mass.
• The main part of the apparatus is the densimeter cell DMA-512P (Anton Paar KG).
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Flow diagram of the vibrating tube densimeter. (1): loading cell; (2a) and (2b): regulating and shut-off valves; (3): DMA-512P densimeter; (4): heat exchanger; (5): bursting disk; (6): inlet of the temperature regulating fluid; (7a) and (7b): regulating and shut-off valves; (8): pressure transducers; (9): vacuum pump; (10): vent; (11): vibrating cell temperature probe; (12): HP 53131A data acquisition unit; (13): HP34970A data acquisition unit; (14): bath temperature probe; (15): principal liquid bath.
Examples of Results VLE measurements
• Vapor Liquid Equilibrium of HFC 245fa (1) +Isopentane (2) at 373.19K • Application for heat pump (used by EDF Les Renardières) • Azeotropic behavior
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0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
P r
e ss
io n
R e
la ti
v e
v o
la ti
li ty
x CO2
Relative volatility :Juntarachat et al. (2014) () at 308.20 K; Raabe (MS) (2013) () at 310.92 K.
P-T and P-x projections including experimental point and modelling using PPR78
Interest in climatisation and/or refrigeration (low pressure glide) The binary system was investigate using two equipments (critical point and static analytic type) R1234yf is considered as one group Parameters are fitted considering both VLE and critical point experimental data Good agreement is observed with molecular simulation calculation
CO2 + HFO 1234yf
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P-ρ diagram for R-1234yf. () Experimental data ; () Confidential Experimental data; () REFPROP; (×) Critical Point: REFPROP (Tc = 367.85K); (- - - -) NEoS; (…...) PT-EoS; ( ) PR-EoS. Out of saturation: Tr = 0.7, 0.9, 1.0, 1.1.
P=RT/(v-b)- a(T)/(v2+ubv+wb2 )
u= 1+ c/b
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P-ρ diagram for R-1234yf. () Experimental data ; () Confidential Experimental data; () REFPROP; (×) Critical Point: REFPROP (Tc = 367.85K); (- - - -) NEoS; (…...) PT-EoS; ( ) PR-EoS. Out of saturation: Tr = 0.7, 0.9, 1.0, 1.1.
P=RT/(v-b)- a(T)/(v2+ubv+wb2 )
u= 1+ c/b
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Similar behavior as the CO 2 + ethane system. Critical positive azeotropy accurately predicted
+CO2
40.0
60.0
x1,y1
P/bar
C2F6 T1 = 227.60 K kij = 0.0870 T2 = 253.29 K kij = 0.0798 T3 = 273.27 K kij = 0.0753
T1 = 283.24 K kij = 0.0734 T2 = 291.22 K kij = 0.0720 T3 = 294.22 K kij = 0.0715 T4 = 296.72 K kij = 0.0711
Examples of results HFO 1216
• Comparison between experimental data (vibrating tube densimeter) and modelling • Patel Teja EoS is used • Necessity to apply a correction (Crossover EoS)
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____: Crossover PT (CR-PT), -------: Classical PT, ×: point critique, () données expérimentales de Coquelet et al.
Density measurements
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0
20
40
60
80
100
120
140
160
Masse volumique [kg/m3]
ar ]
30°C Points de rosée Points de bulle 70°C 50°C 5°C -20°C -10°C 0°C 80°C 75°C
-20°C
70°C
30°C
80°C
• Evaluation of thermodynamic properties of fluids and their mixtures
• Compatibility with lubricant
• Development of predictive equation of state
• Collection of experimental data and measurement of new experimental data (VLE, critical point and density): development of equipment
• Development of specific force Fields and comparison with transport properties data
• Measurement of heat capacity and enthalpy of mixing 27