Kasetsart Engineering Journal

Numerical Study of Flow and Heat Transfer of Water in a Motor Cooling System of Electric Vehicle

ศิวกร เกิงฝาก — 2023-09-07

This research focuses on a numerical study of water flow and heat transfer in a motor’s cooling system using the commercial computational fluid dynamics package, ANSYS-Fluent. A three-dimensional model of water in rectangular was created to have a width of 25 mm, a height of 5.45 mm, and a gap between the channels of 10 mm. The Realizable k-e turbulence model and Standard wall function were used for the computational analysis. The boundary condition of heating walls was defined to be the constant heat flux of 56,523.15 W/m². The water temperature at the entrance of the cooling motor jacket was set to 50 °C and the velocity of 2.4, 4.8, 7.2, 9.6, and 12 liters per minute. The numerical results of flow and heat transfer of water in 3 types of flow channels showed that flow patterns in a cooling system affected the outlet temperature and pressure loss. The change in flow pattern caused the increase in the Nusselt number and the thermal performance factor up to 45.39 % and 31.25%, respectively. Therefore, this research will be important information, leading to the design and development of motor cooling systems to be more efficient in the future.

Effects of Self-Compacting Mortar Partially Replaced Cement with Limestone Powder and Calcined Clay on Slump Flow, Viscosity, and Compressive Strength

บุราฉัตร กิตติกรจรัส — 2023-09-07

This paper presents the effects of partial cement replacement by limestone and calcined clay for producing self-compacting mortar by testing flowability and mechanical properties with slump flow viscosity and compressive strength in order to propose an alternative which is eco-friendly material in construction industry. Amount of cement replacement by calcined clay were 15% and 25%, amount of limestone replacement was 15%. The results showed that the tested viscosity increased when replacing cement by calcined clay of 15% so that it necessary to use higher superplasticizer approximately 2–2.5 times for achieving the suitable slump flow. And it needed superplasticizer of 5–6 times when increasing limestone powder of 15%. Water to binder ratio (W/B) of 40% was suitable because the viscosity of mortar slightly changed with the increase of funnel time not over 3 s after 20 mins after mixing and the initial funnel time was 4–6 s. Replacement amount by calcined clay of 15% resulted in the increased of compressive strength of approximately 20–38% at 28 days with the compressive strength of approximately 700–830 ksc. Moreover, when the replacement ratio was 25% with limestone of 15%, it was found that the compressive strength decreased approximately 15–20% which were 450–490 ksc. Calcined clay can be used to replace cement for producing self-compacting mortar, the mechanical properties was improved and flowability was the most improved with the W/B of 40%. Calcined clay was an alternative material for reducing the demand of cement use.

Bridge Weigh-In-Motion System using Deflection Response

สุพิชฌาย์ ทับพุ่ม — 2023-09-07

This research presents the bridge weigh-in-motion system to identify truck load from bridge deflection response instead of strain. The analysis employs a method of regularized least-squares with accuracy improvement by the updated static component technique applying the direct measurement influence line. The effectiveness is evaluated by numerical examples and statistical studies from computer simulation. The results reveal that analysis using deflection response performs better effectiveness than strain. The appropriate regularization parameter can be selected in the broader range with higher identification accuracy. Bridge surface roughness and measurement noise are significant parameters of system accuracy. The identification error varies to roughness amplitude and noise level. The error can be reduced by smoothening the pavement and using low-noise instruments or applying noise filtering. Using the deflection response is therefore an alternative option to strain that could have a distorted signal if the strain gauge is installed on the microcrack of the concrete surface.

The study of factors that influence the use of high-speed train services in Eastern Economic Corridor (EEC)

Patraphorn Phornthepkasemsant — 2023-09-07

The high-speed railway project is a major infrastructure project in the Eastern Economic Corridor (EEC) that the Thai government has invested in to help the country's economic development. To guarantee that this project provides excellent and timely service, this research aims to identify the factors that affect the utilization of high-speed train services in the EEC. A questionnaire was distributed to 400 Chonburi residents. The majority of individuals are expected to use the train at a proportion of 85.76 percent. The passengers' main goal is to travel. Safety, travel duration, train regularity, service quality, and availability are the top five most important factors. Local pick-up truck-taxi is the most popular feeder between the station and the city region. The route and taxi-stop scheduling, for example, should be improved in the pick-up truck-taxi service. As a result, it will continue to offer excellent railway service to passengers in the long term.

Travel Mode Choice Analysis in Nonthaburi Province Area to Silom Road Area Between Electric Ferry Boat and Purple Line Metro A Case Study of Phra Nang Klao Bridge – Silom

อลงกรณ์ ไชยพรรค — 2023-09-07

At present, one of the most convenient transit modal choices from Nonthaburi to Bangkok’s central business district (CBD), Silom Road, includes an electric ferry boat. In the future, if the purple mass transit Line project in both the northern and southern parts is completed and fully open for service. It will be an alternative public transit mode for Nonthaburi Province to Bangkok CBD Silom Road. The purpose of this research study is to study the modal choice between ferry and rail on Nonthaburi Province to Bangkok CBD Silom Road by utility theory and the stated preference (SP) survey method to investigate respondents’ choice under hypothetical situations. The proposed rail route choice is Phra Nang Klao Bridge area to Silom Road by the Purple Line mass transit system. The target respondent groups surveyed are classified into 1) travelers who have used the electric ferry boat service and 2) travelers who have never used the electric ferry boat. The surveyed data are analyzed to formulate a binary logit model for each respondent’s group. The study results show that the important influencing factors on modal choice decisions include travel time and fare. The proportion of mode changes to Purple Line mass transit system is up to 96.66 percent and 95 percent for those who have used and who have never used the electric ferry boat, respectively.

Development and Parametric Study of Thermodynamic and Heat Transfer Models for a Small Cogeneration Power Plant

Natnicha Musikasang — 2023-09-07

Cogeneration is high efficiency technology and consists of gas turbine, steam turbine and heat recovery steam generator. In the present research study, optimization model of a small cogeneration power plant in Thailand is developed, and the realistic cogeneration model is analyzed and improved by thermodynamic and heat transfer models. The numerical solution is obtained by using MATLAB. Furthermore, the important parameters that affect energy consumption and efficiency are the heat rate of fuel and the valve controlling high pressure at steam turbine outlet. The result from the simulation indicates that for the baseline case the cogeneration efficiency is 56.96% and the Primary Energy Saving (PES) is 16.72%. For the parametric study, by increasing the heat rate of fuel by 3%, the cogeneration efficiency and Primary Energy Saving increase to 57.50% and 17.53%, respectively. On the other hand, by increasing the high pressure at the steam turbine outlet by 7.5 bar, the cogeneration efficiency is nearly a constant and the Primary Energy Saving decreases to 16.62%.

Mathematical modeling of capillary tube designs for refrigeration systems using R410A refrigerant

Supavut Sinprasong — 2023-09-07

The capillary tube is an important device for vapor compression refrigeration systems to control refrigerant pressure and flow rate. Today, there are still many operators who lack the knowledge to use capillary tubes. The choice of equipment is largely based on the experience of the operator and the use of trial and error. Improper and incorrect selections will result in system malfunctions and affect the system's energy efficiency as well. In this work, a mathematical model of the design of capillary tubes for R410A refrigeration systems was developed. R410A was selected for this study as a replacement for R22. Hydrochlorofluorocarbon refrigerants must be discontinued in the near future for reasons of ozone depletion potential. The model evolved from the idea that the refrigerant flowing through the capillary tube changes its properties along the length of the tube through it. The capillary tube is divided into smaller control volumes. The law of conservation of mass, law of conservation of energy, and law of conservation of momentum have been applied to each control volume. The initial parameters consist of the size of the conditioner, the fluid flow rate, and the initial capillary tube size. The model can analyze the properties of the refrigerant, flow velocity, Reynold number, and friction continuously. This model makes the capillary tube design more accurate. It reduces trial and error and reduces the possibility of system malfunctions and failures. Model analysis results in the cooling system operating efficiently and saving energy.

Determination of Mixture Miscibility in Binary and Quaternary Systems of Liquid-Liquid Reactions by Thermodynamics

Issadaporn Wongwanichkangwarn — 2023-09-07

An industrial chemical process commonly involves two types of chemical reaction systems: homogeneous and heterogeneous systems. Identification of mixing state is important in detail modeling of the system. This work focuses on determination of equilibrium mixing state for 3 liquid-liquid reaction systems: 2 types of amidation and transesterification. Each experimental system is binary with two components of reactants at the initial reaction time. As the reactions proceed, each system becomes quaternary with 4 components of 2 reactants and 2 products. The state of mixing of the systems was examined based on the change in dimensionless Gibbs free energy of mixing which was related to liquid activity coefficients. The coefficients were obtained from the UNIFAC method. The results show that the binary mixture of amidation is immiscible in almost all composition ranges except at low reactant concentrations while that of transesterification is immiscible for all compositions of mixture. The mole fraction values used in all systems at the initial reaction time indicate that the binary mixtures are immiscible. As the reactions proceed, the quaternary mixture of amidation is converted to miscible within a short reaction time period due to existing of surfactant produced from the reaction. On the other hand, the quaternary mixture of transesterification is still immiscible throughout the reaction time. At higher reaction temperature, the quaternary mixture of amidation requires a shorter time to convert from immiscible to miscible because of increased rate of surfactant production. The information of mixing state is important for choosing appropriate models in process analysis and design.