مقاله انگلیسی رایگان در مورد آنالیز حسابداری هزینه های گرماسنجی مقایسه ای – الزویر 2018

This study presents an analysis of a biogas engine-powered cogeneration system using four different thermoeconomic methods. The most important parameter is the thermoeconomic cost of work produced by the gas engine for each method. The aim is to compare the results obtained from each of those methods. The first method is the exergetic cost theory, which introduced the exergetic cost concept to the thermoeconomic field for the first time. An incidence matrix is defined to show the interaction of flows and components within the system. Exergetic cost theory defines the main rules and delivers a result of 110.065$/h for the work produced by the gas engine. A second method, modified productive structure analysis, is applied to the system and cost balance equations are formed for each component. Exergy destruction is clearly defined and tabulated. At the end of the analysis, the cost of gas engine work was found to be 85.536$/h. A third new method described in published literature, Wonergy, is used to determine both the cost of work and the heat utilized in the cogeneration system. Wonergy gives the same thermoeconomic cost for the components which help to produce work. The smallest value obtained was 72.5$/h. The fourth method, SPECO (specific exergy cost), was the final analytical method used on the system. It defines fuel and product rules to obtain auxiliary equations. The thermoeconomic cost of work produced from the gas engine was determined to be 141$/h which was the highest value obtained in comparison to the others.

Introduction

In the analysis of the production processes of complex energy systems, the economic profitability and the productivity displayed in resource consumption should both be considered. Performing this analysis, thermodynamics enables us to calculate the efficiencies of the subcomponents that make up the system and determine the locations and amounts of system irreversibilities that occur in the process. However, thermodynamic analysis cannot assess the overall production process in an economic context. Thermoeconomic analysis, by contrast, is a combined discipline that directly assesses the cost of consumed resources, i.e., money and system irreversibilities, within the total production process. While a thermoeconomic analysis shows a variety of ways to use resources more effectively, it also describes the concept of monetary irreversible cost as the economic impact of inefficiency, and it aims to increase the cost efficiency of production processes. Thus, in a detailed thermoeconomic analysis, it becomes possible to understand the flows in the subcomponents and the entire production process, from the perspective of cost, from the raw material sources entering the system to the final products. Thermoeconomic methods are generally divided into two groups: cost accounting [1e5], and optimization techniques [6e12]. Cost accounting is the process of determining the total cost of the production per unit of each output of a thermal system, such as electricity, steam, hot water, chilled water, etc., while optimization methods are applied to finding the optimum design or optimum set of operation conditions. All initial investment and operating costs for establishing and operating a thermal system should be allocated to the final product. Principally, there are two costs that must be defined for each product: (i) Direct costs, which include the cost of resources and materials that are clearly attributable to the product cost throughout the production process, and (ii) Indirect costs. In a comprehensive thermoeconomic analysis, the aim of cost accounting is to establish a logical framework for evaluating the profitability, starting from the determination of the rational costs of the products, to organizing and evaluating the decisions made in accordance with this framework. Valero et al., in their initial work on exergetic cost accounting, developed the basic ideas of their thermoeconomic approach and presented a strong theoretical background. That study, which consisted of two parts, has been accepted as one of the pioneering studies in the thermoeconomic field. In the first part, they identified exergetic and thermoeconomic costs for a relatively simple thermal system and presented the basic conditions for conducting the thermoeconomic analysis of a more complex system [13]. In the second part, they developed the mathematical background for three different applications of the thermoeconomic analysis method described in the first part [14].