detailed programme - SIMS - Scandinavian Simulation Society

therefore not only desirable, but necessary. The main objective in this study is to
create a practical tool to evaluate the state of geothermal reservoirs and well
performances using measured wellhead conditions and inverse analysis. This is to
be done by coupling a wellbore simulator with a reservoir simulator. For this
purpose a new wellbore simulator, called FloWell, is designed. The program
TOUGH2 is used to simulate the flow in the reservoir. The inverse analysis
enables continuous evaluation on estimated parameters in both FloWell and
TOUGH2, such as the permeability, productivity index and the void fraction, and
the measured wellhead conditions provide up to date data to model the current
situation in the geothermal system. A case study involving the Reykjanes
geothermal field is used to validate the wellbore simulator FloWell as well as the
new coupled reservoir-wellbore simulator.
Authors: Halldóra Gudmundsdottir, Magnus Thor Jonsson, Halldor Palsson.
Organization: University of Iceland
Session 8 - Modeling
Paper 3
Title: Development of a multi-level approach to model and optimise the Kalina
Split Cycle
Keyword: Kalina Split Cycle, Multi-Level Modelling, Process Integration
Abstract: Conversion of low-grade heat to power is currently receiving significant
attention, mainly due to increasing fuel prices and the motivation for the use of
sustainable energy. The Kalina cycle, based on a mixture of ammonia and water
as working fluid, is suitable for this purpose and exhibits higher conversion
efficiencies than conventional power cycles.
The split cycle technique provides a method to further increase the thermal
efficiency, by reducing the entropy generation in the heat recovery steam
generator. Two streams of different ammonia concentrations enter and leave the
first evaporator stage at same temperatures and pressures before being mixed at
the inlet of the second evaporator stage.
The multidisciplinary nature of this problem requires modelling at different
system levels. This paper investigates different tools and methods suitable for
demonstrating the feasibility and advantages of the split cycle.
The integrated model developed and presented in this paper combines three submodels
using the NIST REFPROP equations of state: a mass balance model to
handle the high complexity of the split cycle, a component-based model to
optimise the heat exchanger operating conditions, and a process model to
investigate the integration of this process into the overall thermodynamic cycle.
With identical operating conditions, results show a significant increase of the net
power output compared to the baseline case. It is concluded that the split cycle
method could successfully be applied in other thermodynamic cycles, such as
Organic Rankine Cycles.
Authors: Ulrik Larsen, Tuong-Van Nguyen
Organization: Technical University of Denmark