Energy Efficiency of DH System with Wood Chips Boiler Houses and Flue Gas Condensing Unit

This study proposes a method for the evaluation of the efficiency of a heat supply system based on a correlation analysis of the data of the system's operations. The data from the system's operations have been analysed and a correlation equation has been applied to obtain the results of the analysis, which are then used for further calculations. The data can be divided into two groups: data characterising the condenser operations in the boiler house, and data characterising heating networks.

Speed limits and accident rates on highways around the world, is there a correlation?

The objective of this study stands for the investigation and evaluation of accidents that take place on highways, in comparison with speed limits. The main body of this research is based on the collection of highways speed limits from different countries around the globe regarding to years, 2010, 2017 and 2018. Secondly, accident rates are collected from highway authorities, as well as from international literature. Subsequently, a statistical analysis of the collected data is conducted and finally leads to an equation that links and correlates the speed limit values and the number of accidents. The results of this statistical analysis show that speed limit plays a certain and distinctive role in the accident rate value. However, one of the interesting findings, stands for the non-continuously increasing number of accidents in the speed limit range, from the lowest to the highest value, meaning that there is an inflection point in the graph of the correlation equation. To be noted, that in terms of this study, the aforementioned correlation is independent of other factors that could affect the accident rate, such as vehicles condition, technology, road network length and condition.

The Students Willingness and Learning Attitudes Toward Speaking Skill

The purpose of this research is to find out whether or not there was a correlation between the students’ willingness to communicate, and learning attitudes toward speaking skill. This research used a quantitative correlation to find the relationship between the variables. This study’s population consisted of 147 students. The purposive sampling method was used to obtain the sample for this study, which consisted of 25 students from XI IPS 2 and XI IPS 3 classes. The instruments used to obtain data were questionnaires and online test. The questionnaire utilizes a google form with 10 statements and five answers in each statement to assess students’ willingness to communicate, and learning attitudes. The second, test is to obtain the results of each student’s speaking skill, which are recorded. Normality test, homogeneity test, linearity test, bivariate test, multiple correlation equation, and hypothesis test are used to analyze data. Based on data analysis, the multiple regression equation obtained 1.14, implying that there is a very strong relationship between willingness to communicate, and learning attitudes toward speaking skills.

Ignition Delay Time Correlation of C1 - C5 Natural Gas Blends for Intermediate and High Temperature Regime

New ignition delay time (IDT) data for stoichiometric natural gas (NG) blends composed of C1 – C5 n-alkanes with methane as the major component were recorded using a high pressure shock tube (ST) at reflected shock pressures (p5) and temperatures (T5) in the range 20 – 30 bar and 1000 – 1500 K, respectively. The good agreement of the new IDT experimental data with literature data shows the reliability of the new data at the conditions investigated. Comparisons of simulations using the NUI Galway mechanism (NUIGMech1.0) show very good agreement with the new experimental results and with the existing data available in the literature. Empirical IDT correlation equations have been developed through multiple linear regression analyses for these C1 – C5 n-alkane/air mixtures using constant volume IDT simulations in the pressure range pC = 10 – 50 bar, at temperatures TC = 950 – 2000 K and in the equivalence ratio (f) range 0.3 – 3.0. Moreover, a global correlation equation is developed using NUIGMech1.0, to predict the IDTs for these NG mixtures and other relevant data available in the literature. The correlation expression utilized in this study employs a traditional Arrhenius rate form including dependencies on the individual fuel fraction, TC, f and pc.

Inverse Approach for the Average Convection Coefficient Induced by a Forced Fluid Flow Over an Annular Fin of Rectangular Profile Using Tip Temperature Measurements

The objective of the present paper is to develop a simple algebraic computational procedure for the estimation of the average convection coefficient of a forced fluid flow over an annular fin of rectangular profile within the platform of inverse heat conduction problems. The data required is the tip temperatures of an annular fin of rectangular profile, which are measured in an experimental setup. Based on nonlinear regression analysis, an empirical correlation equation is constructed for the dimensionless average tip temperature depending upon the dimensionless thermo–geometrical parameter and the radius ratio. When compared against the outcome of a direct heat conduction problem, the good quality of the estimated average convection coefficient for the annular fin of rectangular profile demonstrates the feasibility of the simple algebraic computational procedure.

Generalized Pitzer Correlation for Density Calculations of Ionic Liquids

The density of ionic liquids is an important design parameter for its utilization as a chemical process solvent. In this study, a generalized Pitzer-type correlation for calculating the density of ionic liquids with the use of reduced temperature (TR), reduced pressure (PR), and acentric factor (ω) as parameters is proposed. Experimental density data were obtained from several references through the IUPAC Ionic Liquids Database. Expansion of the terms as well as integrating the ionic liquid molecular weight was attempted to determine the accuracy improvement of the model in predicting densities at 0.1 MPa. Then, the obtained model was modified by further truncation to include the pressure effects for densities at higher pressures. MATLAB software was used to determine the optimal virial coefficients for the proposed correlations. The percent average absolute deviation (%AAD) was applied to calculate the variation between the experimental and calculated density values. It was concluded that the eight (8) coefficient correlation equation with molecular weight for densities at 0.1 MPa had a %AAD of 4.7537%. Upon modifying the correlation to include pressure effects, the resulting modified equation had an overall %AAD of 4.7174%.

A Model Approach for In-Process Tool Condition Monitoring in CNC Turning Using Machine Vision

Tool wear monitoring and real-time predicting tool life during the machining process is becoming a crucial element in modern manufacturing to properly determine the ideal point to replace tool, remains a challenge currently. In this paper, the model approach for in-process monitoring and predicting progressive tool wear by using machine vision is proposed. The developed method adopts machine vision to acquire tool wear images from a CCD camera. The emerged wear analysis is conducted based on the in-progress of signal processing on captured tool wear images, received throughout the cutting process. This automated analysis is carried out with programming to assess and compare a number of pixels of cutting edge images between cutting tools before machining and during the machining process. The developed system is evaluated through experiments of actual cutting conducted on the CNC turning machine with the proposed system installed to evaluate progressive wear during the machining process. Experimental results are capable of indicating the emerged wear at the current state by comparing the number of pixels between the new and used tools. Average flank wear (VB) is also evaluated linked to tool rejection criteria. The developed system is validated by the 3D microscope measuring actual wear on the used tool after cutting experiments. Comparative wear analysis is then performed by finding the correlation equation of pixels examined by a developed system and SMr2 value measured by the microscope. The results showed that the relationship between the number of pixels and SMr2 is a strong correlation.