1D Simulation of Organic Rankine Cycle
(ORC)
by means of MATLAB
Natthaphon BUN-ATHUEK
1
, Thanapol POOJITGANONT
2,*
,
Heinz Peter BERG
2
and Boonchai WATJATRAKUL
3
1
Department of Mechanical Engineering Technology, College of Industrial Technology,
King Mongkut’s University of Technology North Bangkok, THAILAND
2
Chair for Combustion Engines and Flight Propulsion,
Brandenburg University of Technology Cottbus - Senftenberg, GERMANY
3
Department of Mechanical and Aerospace Engineering, Faculty of Engineering,
King Mongkut’s University of Technology North Bangkok, THAILAND
*Corresponding author
Keywords: Organic Rankine Cycle (ORC), 0D/1D Thermodynamics simulation, MATLAB.
Abstract. 1D thermodynamic simulation of Organic Rankine Cycle (ORC) using MATLAB and
Simulink has been accomplished for investigating an efficiency, net work and power output of the
ORC systems applied for utilizing waste heat from the industrial small power plant. This work is
divided into three parts, which included comparing the simulation results on MATLAB with the
calculation from the numerical commercial program, called Engineering Equation Solver (EES). In
the first section in order to validate the results, the type of working fluid and other working conditions
have been fixed in both programs. The comparing results on T-s diagram, power output and efficiency
at the different operating conditions show that they are corresponding in the same direction. On next
step the results on variations of working fluid have been illustrated. In this section a recuperator has
been also implemented and compared to its effect on the efficiency of the system. In addition, the
variation of heat source temperature, representing the quality of the waste heat, has been studied on
different mass flow rate of Acetone. It is found that for the maximum efficiency, if the heat source
temperature is lower than 800 K, the suitable mass flow rate should not be over than 0.10 kg/s.
1. Introduction
In industries there are a great number of energy losses, i.e. waste heat, during their operation. The
energy will be more worthwhile, if these losses are utilized. In the cold countries, these losses could
be used for warming up the temperature of the room but for the warm countries this could not be
easily done, however, there are also methods to solve such a problem, i.e. using absorption chiller or
applying the ORC system on it.
The Organic Rankine Cycle (ORC) is also a traditional Rankine cycle which uses organic, high
molecular mass fluid as working fluid instead of steam. With a liquid-vapor phase change occurring at
lower temperature than the water-steam phase change, the ORC is a technology for converting low
grade waste heat energy to electricity by the working fluid is expanded in the turbine to generate
power for producing the electricity. The basically configuration of the ORC system consists of four
fundamental components, which are turbine, pump, evaporator and condenser [1-5]. In addition, the
ORC power plant could be claimed that it has low investment cost, high energy conversion efficiency
and unnecessary wastewater treatment system [1]. The schematic diagram could be shown in Fig. 1.
The thermal efficiency of the ORC system could be improved by using a recuperator. In Fig. 1
right the recuperated ORC system is shown. A heat from turbine exhaust is used to preheat the cold
working fluid that leaving the pump before being fed to the evaporator. With this concept the
required power from the heat source could be reduced and the efficiency could be also increased.