Thermodynamic Analysis of Expansion Profile for Displacement-type Expander in Low-temperature Rankine Cycle

Thermodynamic analysis of the isentropic and polytropic expansion profiles of typical working fluids was carried out in order to design a highly efficient displacement-type expander for a low-temperature Rankine cycle. First, expansion profiles were analyzed for three typical working fluids: HFC245fa, ammonia, and supercritical CO 2. The hot-side temperature ranged from 60 ° to 120 °C, and the cold-side temperature was 10 °C. In the analysis, isentropic and polytropic expansion processes were assumed to behave thermodynamically. In the analysis results, we noted similarities among the expansion profiles for different hot-side temperatures. This similarity allowed us to introduce the unique concept of a variable mechanism for expansion profile fitting in displacement-type expanders. This variable expansion mechanism can be achieved by simply adjusting the position of the inlet and/or outlet port of the expander. © 2010 by JSME

Review of Research on Vehicles Aerodynamic Drag Reduction Methods

Recent spikes in fuel prices and concern regarding greenhouse gas emissions, automotive design engineers are faced with the immediate task of introducing more efficient aerodynamic designs vehicles. The aerodynamic drags of a road vehicle is responsible for a large part of the vehicle’s fuel consumption and contribute up to 50% of the total vehicle fuel consumption at highway speeds. Review on the research performance of active and passive flow control on the vehicle aerodynamic drag reduction is reported in this paper. This review intends to provide information on the current approaches and their efficiency in reducing pressure drag of ground vehicles. The review mainly focuses on the methods employed to prevent or delay air flow separation at the rear end of vehicle. Researches carried out by a number of researchers with regard to active and passive flow controls method on vehicle and their effect on aerodynamic drag in terms of drag coefficient (CD) was highlighted. Passive methods i.e. Vortex Generator (VG), spoiler and splitter and active flow controls i.e. steady blowing, suction and air jet are among the methods had been reviewed. In addition several attempts to couple these flow control methods were also reviewed. Several aspects of aerodynamic drag that need for further investigation as to assist for vehicles aerodynamic design and for practical reasons were highlighted. Progressive research on active flow control was observed due to its flexibility for wide range of application without body shape modification

Numerical Simulations of Shear Driven Square and Triangular Cavity by Using Lattice Boltzmann Scheme

In this paper, fluid flow patterns of steady incompressible flow inside shear driven cavity are studied. The numerical simulations are conducted by using lattice Boltzmann method (LBM) for different Reynolds numbers. In order to simulate the flow, derivation of macroscopic hydrodynamics equations from the continuous Boltzmann equation need to be performed. Then,the numerical results of shear-driven flow inside square and triangular cavity are compared with results found in literature review. Present study found that flow patterns are affected by the geometry of the cavity and the Reynolds numbers used

DESIGN OF A SPACE FRAME CHASSIS FOR UTEM PERODUA ECO-CHALLENGE CAR

This paper presents the design of a space frame chassis for UTeM Perodua Eco Challenge car. Several concept designs were generated for the chassis and the final design selected was modeled in 3D using CATIA V5 CAD software during the design stage in the project. Low carbon steel ASTM A36 was selected as the space frame material due to high strength, low cost and versatility with many manufacturing processes. The chassis structural strength was later analyzed using finite element analysis in bending and torsion load cases. Results from the structural analyses showed that the chassis is able to perform safely as per design requirement

INTAKE ANALYSIS ON FOUR-STROKE ENGINE USING CFD

Flow patterns are vital to ensure that the engine can produce high performance with the presence of swirl and tumble inside the cylinder. In this paper, the simulation of air is simulated in the software to predict the flow pattern using the steady state pressure based solver at two different planes in the engine domain. The domain used for the simulation is based on the actual engine parameters. Using the commercial CFD solver ANSYS FLUENT, the CFD simulation is run under five different piston positions and seven different engine speeds. Note that in this simulation, only intake strokes are simulated. The results show the velocity of the flow is high during the sweep as the intake stroke takes place. This situation is believed to produce more swirl and tumble during the compression, hence enhancing the burning rate in an entire region of the clearance volume. The result shows that both for plane A-A and plane B-B, the highest velocity vector occurs when the engine speed at 4500 rpm with piston position at 45 degree. This will initiate to the production of tumble and swirl in the engine cylinder

Quantifying Heat Losses In Micro Combustor With Wire Mesh Using Numerical Simulation

Micro power generation system is a field of study that has come into interest by many researchers due to the strong demands for low weight and long-life power sources of electronic devices. These has led to the increasement of meso and micro-scale combustion investigations. In order to fully understand more on this field of study, a numerical stimulation is utilized to investigate the effect of heat recirculation on the blowout limit for micro combustion. Four different combination of tube combustors is used to investigate their blowout limit such as quartz-brass tube combustion combination for unburned-burned region of micro combustor tube. The combination of tube combustors is then investigated using three-dimensional (3D) numerical simulation. The results suggested that by utilizing brass tube on either region of unburned or burned tube is able to improve the value of heat conducted on inner wall of via inner wall of the tube greatly. Due to the conductivity of brass tube is much larger than quartz tube, the improvement is expecte

Feasibility Study for Energy Recovery from Internal Combustion Engine's Waste Heat.

To mitigate the world’s energy problems and global warming, researchers are focusing on renewable energy, regenerate energy, efficient energy usage and finding alternative energy. In an automobile, Internal Combustion Engine (ICE) also produces heat which is released as waste heat which have a potential to generate energy. Power distribution of an automotive is showing that only about 20% of the power from engine combustion is convert to wheel or driving power and more than 60% of the power will be wasted. One way to convert heat to useful work is by using Rankine cycle. Research study to described the effects of thermal properties of an organic working fluid on the turbine power had also been reported. This research is to investigate the actual potential energy and power from the waste heat released by the an actual passenger car’s ICE through radiator. Feasibility study is conducted, to investigate the capability of the system and to help developing a system that can be used in an actual automobile. With the collected data, an efficient waste heat recovery system for the passenger car’s engine will be develop in the future. From the experiment result, the power output up to 800 W from heat released in the radiator as the temperature difference about 35 C (heat in and out difference). From this study, it is found out there is a significant problem when the radiator cooling fan operates. The power from the waste heat intended to reduce and also becoming unstable. A power storage system and the radiator cooling fan control will be vital to obtain high usable energy from ICE heat

Prediction of generated power from steam turbine waste heat recovery mechanism system on naturally aspirated spark ignition engine using artificial neural network

The waste heat from exhaust gases represents a significant amount of thermal energy, which has conventionally been used for combined heating and power applications. This paper proposes a prediction model on the performance of a naturally aspirated spark ignition engine equipped with a waste heat recovery mechanism (WHRM) using steam turbine mechanism. The simulation method is created using an artificial neural network (ANN) to predict the power produced from this WHRM. The automated neural network was employed to run the simulation, where the ANN analysis used multilayer perceptrons as the network architecture, which is a feed-forward neural network architecture with uni-directional full connections between successive layers and applied Broyden–Fletcher–Goldfarb–Shanno algorithm iterative techniques to train the data. By using ANN, power generated from this WHRM could be predicted with good accuracy of 0.007, 0.011, and 0.016% error on training, test and validation data, respectively

Analysis Of Parameters Assessment On Laminated Rubber-Metal Spring For Structural Vibration

This paper presents the analysis of parameter assessment on laminated rubber-metal spring (LR-MS) for vibrating structure. Three parameters were selected for the assessment which are mass, Young’s modulus and radius. Natural rubber materials has been used to develop the LR-MS model. Three analyses were later conducted based on the selected parameters to the LR-MS performance which are natural frequency, location of the internal resonance frequency and transmissibility of internal resonance. Results of the analysis performed were plotted in frequency domain function graph. Transmissibility of laminated rubber-metal spring (LR-MS) is changed by changing the value of the parameter. This occurrence was referred to the theory from open literature then final conclusion has been make which are these parameters have a potential to give an effects and trends for LR-MS transmissibility