This paper describes the development of a high performance
low pressure turbine (LPT) for turbocompounding applications
to be used in a 1.0 litre ”cost-effective, ultra-efficient gasoline
engine for a small and large segment passenger car”. Under this
assumption, a mixed-flow turbine was designed to recover latent
energy of discharged exhaust gases at low pressure ratios (1.05 -
1.3) and to drive a small electric generator with a maximum
power output of 1.0 kW. The design operating conditions were
fixed at 50,000 rpm with a pressure ratio of 1.1. Commercially
available turbines are not suitable for this purpose due to the
very low efficiencies experienced when operating in these
pressure ratio ranges.
The low pressure turbine performance was simulated using a
commercial CFD software. Then, turbine performance was
validated with a comprehensive turbine testing that was
accomplished by using the Imperial College turbine test rig. The
testing and the simulation conditions were conducted for a range
of design equivalent speeds spanning between 80% and 120% at
steps of 10% increase.
In addition, the impact of the turbocompounding on Brake
Specific Fuel Consumption (BSFC) and Brake Mean Effective
Pressure (BMEP) was also assessed by using a 1-D validated
engine model of the engine under study. Three different
arrangements for the turbocompounding were assessed: (1) precatalyst,
(2) post-catalyst and (3) in the wastegate of the main
turbocharger. The outcomes of the simulation were compared to
those obtained for the baseline engine and are discussed in the
the paper. The 1-D engine simulation had shown that the
maximum benefit of the turbocompounding can be achieved when
it was located at the post catalyst with maximum BSFC reduction
of 2.4% at 1500 rpm and 3.0% of BMEP increase at 1000rpm.
This paper presents the development of numerical methods for
modeling non-equilibrium condensing flows in steam turbines.
The method is within Eulerian-Eulerian Framework. A Roe
convective flux is derived, which is featured on using real steam
property and fully coupling wetness fraction with other
conservative variables in the Jacobian matrix. The analytical
expressions of eigenvalue, right and left side eigenvectors are
derived. The real steam property treatment is enlightened by the
two-dimensional TTSE method, and the current paper extended it
to three dimensions which exhibits great convenience for
Quadrature Method of Moments (QMOM) is implemented to
model polydisperse droplet spectrum. To overcome instable issues
caused by moment corruption, which is inevitable during steady
state time marching, a correction scheme for moments is applied.
Example calculations on nozzles and a turbine cascade are
provided. Results show that the current model is robust and correct.
QMOM is capable of representing the polydisperse droplet
spectrum. Correction schemes play a crucial role for the stability
and accuracy of QMOM.
This paper presents an original control system design that enables
electrical load-following with GTHTR300C, a nuclear gas
turbine cogeneration plant under development by JAEA for potential
deployment in developing countries. The plant operates on a
closed Brayton cycle directly heated by the helium gas coolant of a
small-sized Generation IV High Temperature Gas-cooled Reactor
(HTGR), also known as Very High Temperature Reactor (VHTR).
The control system is designed to follow daily electric load by
taking advantage of the unique operation characteristics of the
nuclear reactor and closed cycle gas turbine and the direct interface
of the nuclear heat source and gas turbine engine. The control
system integrates several fundamental control methods and permits
wide-ranging load follow at constant reactor power and high
thermal efficiency, which maximizes plant economics.
Control simulation of the overall plant system to follow daily
load changes representative of developing countries are performed
using a system analysis code in order to demonstrate a technical
feasibility of the system. The observable operation parameters
essential to the system control are identified that include reactor
outlet temperature, turbine inlet temperature, gas turbine rotational
speed, and so on. The simulations results show that the load-follow
can be effectively carried out by monitoring these parameters and
controlling them with suitable control apparatus.