Journal of Building Engineering 32 (2020) 101429 Available online 8 August 2020 2352-7102/© 2020 Elsevier Ltd. All rights reserved. Overview and implementation of dynamic thermoeconomic & diagnosis analyses in HVAC&R systems Ana Picallo-Perez a, * , Andrea Lazzaretto b , Jos´e M. Sala a a Research Group ENEDI, Department of Thermal Engineering, University of the Basque Country (UPV/EHU), Alameda Urquijo, S/N, 48013, Bilbao, Vizcaya, Spain b University of Padova, Department of Industrial Engineering, Via Venezia 1, 35131, Padova, Italy A R T I C L E INFO Keywords: Exergy analysis Thermoeconomics Diagnosis Dynamic systems HVAC&R systems ABSTRACT The purpose of this paper is to apply thermoeconomics in a HVAC&R facility in order to implement the dynamic behaviour as well as to solve the direct problem of diagnosis. New methodological aspects of thermoeconomic applications are developed, such as a new method for setting the productive dynamic structure, in particular to define the commonly used three-way valves and the inertial components. Besides, a novel easy-to-use method- ology is explained to filter the induced effects; and, consequently, a new way to solve the direct problem of the diagnosis is obtained. Some crucial aspects of Second Law applications are discussed and all of this is applied to a real HVAC&R system using data from an experimental test in which a two-fault operation condition was deliberately assigned. The results demonstrate that this new thermoeconomic methodology can be applied to systems that behave dynamically to obtain extra information in costs distribution and in the evaluation of the effects of anomalies; and the method is particularly relevant when the dynamic behaviour of the components needs to be contemplated. In summary, the novelty of this research is to go a step forward in thermoeconomic applications, developing a new methodology to be implemented in dynamic systems for fault detection and diagnosis, using a critical point of view. 1. Introduction The problem of minimizing the consumption of natural resources can be handled by taking into account the useful work that can be extracted from an energy flow and measured by exergy. Exergy combines the First and the Second Law of thermodynamics and it enables to quantify the inefficiencies due to irreversibilities [1]. Then it allows detecting the degradation of energy [2] and represents a synthesis of thermodynamic information; so, it is useful for outlining the energy behaviour [3] of components and makes the comparison between different systems. Be- sides, labor and capital can be converted into exergy terms and their equivalent can be included by extended exergy methods [4]. Nevertheless, exergy is meaningless without a reference state or dead state that shows the capability or limit for the useful work; hence, rel- ativity is the main feature of exergy analysis [2]. Moreover, as ther- moeconomic properties are a combination of several physical properties, they include information in aggregated form and, therefore, a part of the original information is “covered” when converting physical magnitudes to exergy parameters. Moreover, the Second Law on its own is not suf- ficient to explain accurately the efficiency (physical and geometric pa- rameters need to be considered as well). In any case, although exergy is expressed as a combination of dependent thermodynamic properties [5], it provides relevant information for the phases of design, optimization or maintenance of any energy system. 1.1. Brief review of the Second Law applications in energy systems Second Law analyses of energy systems started having reasonable impact in the middle of the 60’s and, therefrom, great improvements have been pursued until current days. One of the major achievements of exergy method implementation, developed in the 80’s, was the exergy cost accounting [6], included in the science of Thermoeconomics, which allocates the cost of flows according to the process irreversibilities. Thereby, the application of thermoeconomics has been on the scope of many researchers that develop different methodologies. Among others, Exergy Economics Approach (EEA), [7]; First Exergoeoconomic * Corresponding author. E-mail address: ana.picallo@ehu.eus (A. Picallo-Perez). Contents lists available at ScienceDirect Journal of Building Engineering journal homepage: http://www.elsevier.com/locate/jobe https://doi.org/10.1016/j.jobe.2020.101429 Received 19 September 2019; Received in revised form 6 April 2020; Accepted 12 April 2020