Two-Phase Flow (AC, Rankine)
Fast and Robust Simulation of Two-Phase Flows
GT-SUITE has a capability for solving two-phase flows. It is based on the same proven flow solver used for a wide range of fluid simulations in GT-SUITE, such as engine gas dynamics on one hand, and fuel injection and hydraulics on the other hand. The only difference is in the definition of the thermodynamic properties of the fluids and two-phase flow heat transfer. The treatment of the thermodynamic properties is based on the NIST library REFPROP. The heat transfer calculations are based on standard two-phase flow correlations. In addition, user heat transfer correlations can easily be added to supplement the provided list of two-phase flow correlations. The model is completely transient, to allow a broad range of investigations. Because of its strong fundamental flow solution methodology, it is very robust and allows the simulations start from an arbitrary starting point. The code execution is fast, running faster than real-time. The main applications of the two phase capability are for air conditioning and for exhaust heat recovery.
Air Conditioning
GT-SUITE models all types of air conditioning systems. It includes fixed orifice tube and accumulator systems, as well as thermal expansion valve (TXV) and receiver/dryer systems. It also handles transcritical systems (e.g. CO2). As with all GT-SUITE models, these models are object oriented which allows for optimum flexibility and creation of various configurations such as branched multi-evaporator systems, cascading cycles, as well as open-circuit modeling for component calibration.
Figure 1: Transcritical (CO2) System
Cabin Modeling
Modeling of air conditioning includes also the modeling of the passenger cabin. There are two models available in GT-SUITE. One is a lumped analysis, using a modular cabin object. This object can be used to build-up a multi-volume representation of the cabin to various degrees of detail. A separate capability is to use the CAD preprocessor COOL3D to build a 3-D model of the cabin (see below).
Figure 2: Temperature field in the 3-D model after 60 seconds from start.
Exhaust Heat Recovery (Rankine cycle)
A popular application for the two-phase flow capability is Rankine cycle as applied to exhaust heat recovery. There are several sources of heat rejected from an engine, such as through exhaust pipe, in CAC and EGR cooler. The concept of exhaust heat recovery focuses on utilization of this heat energy, which would be otherwise wasted, into useful work, to produce additional engine torque or electricity. Evaluation and optimization of such a concept requires a fairly complete system modeling, including the engine, Rankine cycle circuit, and a device for energy extraction, in this case (see below), a turbine driving an electric generator.
Figure 3: Exhaust heat recovery using the Rankine cycle
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| Gamma Technologies, Inc. 601 Oakmont Lane, Suite 220 Westmont, IL 60559 USA |
Tel. Fax. (630) 325-5849 Email:CAE@gtisoft.com Web:www.gtisoft.com |
APPLICATIONS
Engine Performance
Test Pressure Analysis
Exhaust Aftertreatment
Acoustics
SiL, HiL, real-time
Vehicle, driveline
Hybrid Vehicles
Cooling/VTM
Underhood Modules
AC and Rankine
Lubrication and bearings
Fuel Injection
Hydraulics, pneumatics
Valvetrain, camshaft
Cranktrain, crankshaft
Chain, gear, belt drive