3 rd International Seminar on ORC Power Systems October 12-14, 2015, Brussels, Belgium

Transcription

1 3 rd International Seminar on ORC Power Systems October 12-14, 2015, Brussels, Belgium THERMODYNAMIC SIMULATION AND EXPERIMENTAL VALIDIATION OF A CASCADED TWO-STAGE ORGANIC RANKINE CYCLE Paper ID: 197 Frithjof H. Dubberke*, Klaus-Peter Priebe*, Jadran Vrabec* Maximilian Roedder, Matthias Neef University of Paderborn*, Universtity of Applied Sciences, Düsseldorf Germany

2 Overview Introduction/Aim Cycle design System construction System operation Conclusions

3 Well proven, conservative ORC-design with thermal-oil-circulation, working circulation and cooling circulation Abgasstrom Jenbacher 3 Turbine Flue Gas 2 Abgas-WÜ Verdampfer 4 Pumpe WKL 1 Vorwärmer Kondensator Rückkühler 1 Turbinenkreislauf Working fluid circulation Pumpe Thermal-oil Abgaswärmekreislaufcirculation Cooling Kühlkreislauf circulation 0 Pumpe KKL Disadvantages: large number of parts, pumps and sensors etc., less flexibility facing demands for electricity and heat (coldness)

4 Aiming at the recovery of exergy from waste heat Maximize the performance of the CORC process by employing zeotropic mixtures Identify fluid combinations with respect to exergetically favourable characteristics during heat transfer in the evaporator Schematic example Subcritical HT cycle with a zeotropic mixture in operation Supercritical LT cycle with a pure fluid in operation

5 Abgaswärme 4 Turbine 1 Advantages of two-stage ORC-circulation: 2 5 Exergetic efficiency high flexibility 6 Kühlkreislauf Different operational modes for customers: 1 Pumpe 1 HT Turbinenkreislauf cycle 1 Turbinenkreislauf 2 0 Motorwärme LT cycle Exhaust Abgaswärmekreislauf heat Motorwärmekreislauf coolant cycle ORC Kühlkreislauf Cooling cycle Pumpe 2 0 Turbine 2 5 Kühlkreislauf electrical power production and maximum heat for warming variable power production and variable heat for warming maximum electrical power production

6 Cascaded two-stage organic Rankine cycle The HT cycle cools the sensible waste heat source down to low temperatures The LT cycle is linked to the HT cycle via a heat exchanger, which acts as condenser for the HT cycle as well as an evaporator for the LT cycle

7 CORC construction 1: 2: 3: 4a: 4b: 5: 6: Pump heating cycle Heat exchanger (HE1) Heat exchanger (HE2) Feed pump (HT) Feed pump (LT) Condensers Turbine+generator (HT) The evaluation studies are also focussed on technical and economical efficiency facing customer needs

8 System information Heating cycle Driven by a pump for mass flows of up to 450g/s and 45 bar Heated by four electric heating rods each with 50kW Fully variable adjustable from 0-200kW up to 350 C Turbine design Application for testing different working fluids Therefore, its efficiency is initially subordinate Feed Pumps Progressive cavity pumps Cooling cycle Air cooled ethylene-glycol/water cycle Connected via plate heat exchanger to the HT and LT cycle

9 Axial inlet and zentrifugal outflow Laval nozzle design for mach 2,5 in the rotating turbine disc Construction is able to work with wet vapor Hermetic turbine-generator design with magnetic coupling CORC turbine

10 Construction of CORC The piping is designed for temperatures up to 350 C and 45 bar pressure in operation Heat production is realized by electrical heating with 4 x 50 kw in a thermooil circulation Plate heat exchangers are also used for condensation at 6 bar

11 Cooling Cycle The cooling and condensation circulation works with H2O- Glykol and a cooler outside of the container The ventilation of the cooler outside is guided by the environmental temperature

12 CORC control unit ThEt

13 Operating systems HT cycle LT cycle HT working fluid: Expansion: Turbine inlet (h 2 ): Heat input: Cyclopentane Turbine 228 C; 28bar 98kW LT working fluid: Expansion: Throttle inlet (h 7 ): Heat input: MM Throttle 170 C; 7.7bar 10kW

14 Test rig used for experimental studies on high speed flash evaporation

15 Preview to upcoming ORC-design Direct evaporation Direct liquefaction Variable design for power and heat production First designs with new zeotropic mixtures realizing temperature glide if better efficiency than toluene Supercritical circulation

16 Thank you for your attention!