Low grade thermal recovery based on trilateral flash ... · aDavide Di Battista a, Fabio Fatigati a University of L’Aquila, Via Giovanni Gronchi 18, L’Aquila 67100, Italy . b.

1st International Conference on Sustainable Energy and Resource Use in Food Chains

RCUK Centre for Sustainable Energy Use in Food Chains

Low grade thermal recovery based on trilateral flash cycles using recent pure

fluids and mixtures Roberto Cipollonea, Giuseppe Bianchia,b, Marco Di Bartolomeoa,

Davide Di Battistaa, Fabio Fatigatia

aUniversity of L’Aquila, Via Giovanni Gronchi 18, L’Aquila 67100, Italy bBrunel University London, Kingston Lane, Uxbridge UB8 3PH, United Kingdom

Windsor, 20/04/2017



Outline

2 D. Di Battista - University of L’Aquila

Low thermal grade energy recovery

Carbon dioxide refrigeration plant

Trilateral Flash Cycle

Expander selection

Fluid screening (pure and mixtures)

Mathematical model of TFC recovery plant

Results and discussion on real behavior of volumetric machines

Conclusions



Low grade thermal sources

3

Renewable energies (solar, geothermal, ocean,…)

Industrial processes (steel, glass, oil, chemical, …)

Compressed air (lubricating oil)

Energy transformation sector

Micro-CHP (domestic applied to the heating boilers)

Transportation sector (ICEs)

D. Di Battista - University of L’Aquila



CO2 refrigeration plant at UNIVAQ




CO2 refrigeration plant at UNIVAQ




CO2 refrigeration plant

6

Pcomp=16 kW

Pgas cooler=30 kW




CO2 refrigeration plant recovery

7

Via ORC Via ORC-mixtures Via ORC-mixtures transcritical

Via TFC


HEAT EXCHANGER



Trilateral Flash Cycle

8

T-s diagram - R1234ze(E) at maximum power configuration

1 kg/s CO2




Suitable Expanders

9

10 100 1000 10000 100000Electric output [kWe]

0

100

200

300

400

Sou

rce

tem

pera

ture

[°C

]

Fluid stabilitylimit

No. stagesHigh costs

Steam

Small ORCHigh temperatures

Mainstream ORC

Large ORCLow temperatures

Mic

ro-C

ogen

erat

ion

Small ORCLow temperatures

101 102 103 104 105


Volumetric machines



Mathematical Model

10

, ,

3 2

( )hs hs in hs outm h hm

h h−

=−

( )3 4 2 1( )P m h h h h = − − −




Parametric Analysis

11

Parametric analysis on R1234ze(E)

( )3 4 2 1( )P m h h h h = − − −




Working Fluid Selection: Mixtures




Working Fluid Selection

13

Specific power output and working fluid flow rate at maximum power conditions












Expander and fluid matching

16

Target expander built-in volume ratio to match the TFC




Expander experimental behaviour

17

( ),

1

d id

d

V

V

P p p dV∆ = −∫

loss

Built-in discharge volume




Expander experimental behaviour

18

Isochoric discharge




Real expander behaviour

19

Mechanical power vs expander built-in volume ratio (mixtures)

Net power output vs expander built-in volume ratio (pure fluids)




Conclusions

20

• TFC suitable for low temperature thermal sources recovery

• Complexity due to the wet expansion volumetric machines

high volumes ratio

• Importance of the fluid selection

• Real behaviour of the volumetric expander

final isochoric discharge

use of mixtures lead to a lower discharge losses

• Thermal source considered: 1 kg/s trans-critical CO2 from 100 °C to 40 °C

(food refrigeration gas cooler)

best fluid: R1234ze 6.5 kW at 21 bar max pressure and BIVR>14

best mixture: Propane/CO2 0.9/0.1 3,5 kW and BIVR<4.5


Low grade thermal recovery based on trilateral flash ... · aDavide Di Battista a, Fabio Fatigati a University of L’Aquila, Via Giovanni Gronchi 18, L’Aquila 67100, Italy . b.

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