ABSTRACT. Welcome Note

ABSTRACT. The presentation will provide an update of the EU energy efficiency legislation on electric motors and motor systems. It will include a highlight of the political context in the frame of the new Commission being set up after the European elections, as well as a detalied update of the legislative proposals being prepared.

ABSTRACT. The United for Efficiency (U4E) Initiative, led by the United Nations Environment Programme (UNEP) - has published an Electric Motors Systems Policy Guide (PG) and a set of Model Regulation Guidelines (MRG) to assist developing countries and emerging economies transform their markets to adopting energy-efficient electric motor systems using the systems approach.

The MRG provide ready templates to set minimum efficiency performance standards (MEPS) for (a) motors, (b) variable speed drives, (c) industrial fans, (d) rotodynamic water pumps for pumping clean water, and (e) standard air compressor packages. 

The MRG are structured as building blocks that may be combined based on the market structure and practices in each individual country or region. These include all the key elements that are needed for this type of regulation: (i) definitions, (ii) scope, (iii) performance requirements, (iv) product information requirements, (v) applicable test methods and (vi) compliance criteria. The MRG are adaptable to country circumstances e.g., for motors – more stringent MEPS equivalent to current international best practices for countries that do not have a significant domestic manufacturing industry and less stringent MEPS as start for other countries that have a significant domestic manufacturing industry to provide (limited) transitional time for upgrading technology.

The Policy Guide provides policy makers with a step-by-step approach for implementing all elements of energy efficiency policy while highlighting global best practices and providing examples cases. Three routes are highlighted, firstly for improving the efficiency of new equipment with (a) the development and implementation of mandatory MEPS and providing in (b) monitoring, verification and enforcement; Secondly for improving the efficiency of the installed base through (c) supporting policies such as accelerating motor replacements, and motor management and utility DSM programs; and, Thirdly through overarching policies i.e., (d) communications & awareness building, training & capacity building including M&V, voluntary agreements, energy performance targets, energy management, energy audits; (e) Finance and delivery mechanisms such as grants, rebates, incentives, tax-relief, credit lines and risk guarantees, leasing, and ESCO’s, (f) Environmentally sound management using circularity principles. 

ABSTRACT. The United States Department of Energy (DOE) was first granted the authority to develop, implement, and revise energy conservation standards for a variety of consumer and commercial products through passage of the Energy Policy and Conservation Act (EPCA) in 1975. EPCA requires the DOE to revisit its energy conservation standards, or efficiency minimums, for the majority of products every six years. The regulatory process as defined by statute, while public in nature, creates a constant cycle of reactive activity on the part of industry and other stakeholders. The traditional regulatory process does not typically allow for productive collaboration across stakeholder groups with diverse interests.

The United States (US) electric motor industry has a history of utilizing an alternative regulatory process known as a negotiated rulemaking to shape the final outcome of DOE standards. However, in the past these negotiations were handled as singular events with only one outcome in mind – consensus on a set of specific amended energy conservation standards. While these negotiations enabled more proactive, collaborative engagement across industry and with DOE, these negotiations only provided industry with a regulatory roadmap spanning five to ten years.

During the latest round of DOE regulatory activity pertaining to motors, industry formed a coalition with energy efficiency advocates and utility representatives to develop both a test standard and a set of proposed energy conservation standards for the current cycle, as well as a shared vision for the long-term future of the US motor market.

Recognizing the higher contribution of variable speed technology to lower energy consumption as compared to motor efficiency alone, as well as the current trend among motor and drive manufacturers to adopt these technologies, the “Motor Coalition” is actively developing a multi-pronged approach to drive the motor market towards increased adoption of variable speed technologies. The Coalition is focused on the following actions: (1) development of a new efficiency metric and standardized test methods that more accurately represents the benefits; (2) identification of barriers and execution of regulatory changes that will remove barriers to greater adoption; and (3) implementation of voluntary programs to accelerate market transformation towards variable speed.

The Motor Coalition’s unique and collaborative approach will provide increased certainty and a long term roadmap for US motor manufacturers, while simultaneously ensuring significant energy savings can be achieved through electric motor regulations and their extended products. This paper analyzes the process undertaken by the Motor Coalition, identifies best practices and lessons learned, and discusses likely outcomes of Coalition activities on the future of the US motor market.

ABSTRACT. Energy Efficiency regulations covering induction electric motor are reaching a point of diminishing -and in some cases negative returns for consumers. The large increases in cost in product redesign and installation changes to accommodate larger motors, higher inrush characteristics, and supplementary control equipment often outweigh cost savings generated by the incremental increases of efficiency. Finding ways to save energy for products employing electric motors requires thinking about regulating motors in a new way. The focus must shift from increasing efficiency of a component to reducing power used. For variable torque loads such as fans, blowers and rotodynamic pumps, the ability to match the power use at lower speeds to the load required is significant While many efforts are underway to encourage adopting variable speed motors in these applications, there is currently no accepted standardized approach to measure fixed speed and variable speed motor energy use. The challenge is to develop a test and measurement method that allows comparison of power usage between fixed speed induction, fixed speed synchronous, and variable speed motor systems, which provides a consistent means for measurement or regulation. This paper reviews and summarizes recent efforts by motor and drive manufacturers (represented by the National Electrical Manufacturers Association) and energy advocates (with assistance from the Department of Energy) to develop a metric to quantify the energy savings benefits of variable speed motor-drive systems compared with conventional fixed speed motors.

ABSTRACT. An accurate knowledge of the power dissipation and efficiency of an inverter-fed motor is essential, whereas a precise measurement with a high resolution of measurement points is very time consuming and cost intensive. In the standard IEC 60034-2-3, seven standardized measuring points are used to determine the losses and efficiencies throughout the whole base speed range of an electrical machine. However, the used correlation is not applicable to the fieldweakening and overload range, whereas those regions are of enormous importance for a speed-variant drive system. In this contribution, we present an approach to extend the existing interpolation approach in IEC 60034-2-3 to estimate the losses and efficiencies between standstill and twice the rated speed as well as between no-load operation and twice the rated torque. The approach is based on the seven standardizes measurement points and no additional measurement is needed. Furthermore, the influence of a switching from a star-connection to a delta-connection and from a star-connection to a double star-connection is investigated.

ABSTRACT. The paper presents the magnetic characterization of the nanocrystalline material for use in the stator core of the axial flux motor considering the effects of heat treatment, core potting and the frequency range of the motor application. The nanocrystalline soft material is obtained by rapid quenching from metal consisting of Fe, Si, B and some amounts of Cu and Nb with a specific heat treatment to create the grains which are extremely uniform and small in nanometer scale. These materials have attractive properties as low losses and high permeability in the high frequencies and offers excellent performance in terms of electromagnetic noise suppression due the small magnetostriction coefficient due the weak anisotropy of the magnetic crystal. The saturation magnetic induction of this material is slightly lower than that of commonly used silicon steel in electrical machines. Currently, the main applications of this material are magnetic components for electronic devices such as common mode chokes, high frequency power transformer, switch power supplies, inductors and current sensors, where the materials are characterized at high frequencies in the order of megahertz. In electric motors application is necessary to characterize the nanocrystalline soft material at low and medium frequency in the order of 50 to 1000Hz, considering the magnetic induction range up to magnetic saturation. The paper will present the results of magnetic characterizations and axial flux motor finite element analysis comparing with the laboratory tests results which despite the manipulation challenges arising from physical properties of the nanocrystalline soft material, the motor had a significant reduction in the iron losses at high frequency increasing its efficiency level in comparison to the same project based on silicon steel, which is the material traditionally used in the manufacture of electric motors. This gain led to a considerable reduction in the operating temperature and consequent increase in the power density of the motor.

ABSTRACT. The use of independent ventilation as a cooling method for large rotating electrical machines has proven to be an excellent solution for low-speed machines with high output power or machines with variable speed operation. In both situations, the use of forced ventilation with fixed rotating speed is the most used solution to meet the cooling requirements of the electrical machine. However, when associated with a VFD system, it becomes possible to vary the speed of the cooling fans according to the demand of the ventilation system. Taking advantage of the cubic variation between fan power consumption and its rotation speed, it is possible to reach substantial savings in electrical energy consumption used to drive the fan motors when the electric machine operates below its nominal operating conditions. In this paper, studies are conducted on savings of electrical energy consumption of independent ventilation motors in scenarios where the main machine operates below the nominal ambient temperature and cases where it runs with reduced power.

ABSTRACT. The air compressor stock in China reached about 3 million in 2020. Air compressor systems are responsible for over 9% of electricity consumption in the industrial sector in China, amounting to roughly 550 TWh of electricity in 2023. The air compressor system is composed of a complex combination of various com-ponents and equipment designed to deliver high-quality compressed air to industrial users in production activities and has higher energy-saving potential. The driving electric motor presents an improvement potential ranging from approximately 1.4% to 3%. There remains a notable opportunity for enhancing energy efficiency in air compressors by 10% to 20%. However, achieving such a substantial enhancement entails significant costs and may pose challenges to the economic feasibility for motors and compressors. The significance of compressed air dryers has long been underestimated. However, analysis indicates a wide-ranging energy efficiency enhancement potential for dry-ers, ranging between 10% to 20%, or even greater, at reasonable costs. According to the Chinese industry standard T/CGMA 033001-2018, the efficiency disparity between average and the most efficient compressed air systems can reach up to 45%. Since 2000, with the further advancement of screw air compressor miniaturization technology, the market has witnessed the emergence of Integrated Compressed Air Equipment (ICAE) as a novel type of system-oriented product. ICAE offers numer-ous advantages, including tailored compressed air supply to match demands at the point of use, heightened energy efficiency for air compressors, enhanced drying processes, integration of centralized control technology and variable frequency speed regulation technology, reduced operating pressure, optimization of pipeline networks, enhanced leakage control, and utilization of compressed air heat recovery. Market research reveals that over 200 Chinese manufacturers produce and promote ICAE in the Chinese market. It is anticipated that ICAE will represent over 50% of the total number of air compressors. Standardization efforts concerning energy are crucial for promoting ICAE in the market. China initiated the development of product standard for ICAE in 2023. The proposed standard encompasses the product scope, new energy efficiency metrics, testing conditions, testing and efficiency calculation methodologies, and a voluntary energy efficiency classification scheme. In conclusion, China's consumption of compressed air energy is substantial, present-ing significant potential for energy savings in systems. The market outlook for ICAE products is promising, and standardization efforts for ICAE products are imperative. It is recommended for Chinese policymakers to consider establishing mandatory energy efficiency standards for ICAE.

ABSTRACT. To align with global climate change mitigation goals, industrial companies are reassessing their carbon footprint. This reevaluation is spurred by heightened industry awareness of its contribution to global warming, with government incentives and regulatory requirements further propelling this commitment. High-energy consumption sectors, particularly air compression, which accounts for 10% of global industrial electricity consumption and 5% of global electricity use, are receiving special attention. In response, companies are dedicated to reducing greenhouse gas (GHG) emissions associated with their air compression operations. These efforts involve minimizing gas leaks, reducing pressure drops, and adopting more efficient energy management practices. A pivotal strategy involves embracing variable-speed technology, enabling compressor speed adjustments based on compressed air demand, leading to enhanced energy efficiency. Another crucial consideration centers around the choice of compressor types. Companies now face the strategic decision of selecting the compressor type best suited to their unique needs. This decision depends on factors such as facility size, fluctuations in compressed air demand, operational constraints, and heat recovery capabilities. Active magnetic bearing (AMB) technology has gained prominence across various fields, making an in-depth discussion of its operating principles and control mechanisms unnecessary . Its application in areas like chillers and turbo blowers has demonstrated significant energy savings, resulting in an almost 30% reduction in carbon footprint compared to traditional "oiled compressors". Furthermore, the sealed design of compressors using AMB in gas applications minimizes gas leaks, further mitigating the carbon footprint . Recent comparisons of energy savings and CO2 emissions between a three-stage compression unit equipped with variable-speed magnetic-bearing centrifugal compressors operating at 35000 rpm and a two-stage unit with oil-free screw compressors operating at 3000 rpm, both utilizing variable speed, have emphasized the significant energy and carbon emissions reductions achieved by the centrifugal solution, amounting to minimum 10%. In this study, our aim is to highlight how increasing the speed to around 60000 rpm can significantly enhance the specific energy efficiency of a three-stage compression unit equipped with a centrifugal compressor. Our analysis will focus and energy consumption ucomparing three compression units: a three-stage centrifugal compression unit capable of operating up to 60000 rpm and another three-stage centrifugal compression unit designed to operate up to 35000 rpm.

ABSTRACT. Compressed air system optimization Sandie B. Nielsen Søren Draborg Claus M. Hvenegaard Danish Technological Institute, Department of Energy & Climate Abstract There are considerable opportunities for increased efficiency in compressed air systems that can be realized through demand-based control methods and use of energy efficient components. Experiences from studies show that in many cases a potential of up to 30% still can be realized despite years of focus on energy efficiency. The primary purpose of the project was to develop a calculation tool for compressed air systems, which enables the user to quickly and easily make calculations of different configurations of air compressors with varying capacity control. The calculation program is accompanied by a user guide that illustrates the use of the calculation tool. In connection with the above-mentioned calculation tool, a guide in design of energy-efficient compressed air systems has been developed, as the experience is that the interaction between the capacity of compressors, air treatment, compressed air tanks and the overall control of the installations in relation to the actual needs is far from optimal. In addition, a guide has been developed in which it is explained how measurements should be performed on compressed air systems. The development of the calculation tool has taken place in close collaboration with a supplier of compressed air systems, an educational institution and an industrial company represented by:  Kaeser Kompressorer A/S Denmark  The Mechanical Engineering School Copenhagen  Topsoe A/S The project was funded by the Danish ELFORSK program and the participating companies was led by Danish Technological Institute.

ABSTRACT. The EUropean MOtor REnovation initiative (EU-MORE), co-funded under a LIFE grant agreement, aims to accelerate the replacement rate of old, inefficient motors through the development of new policies. Organisations tend to operate electric motors for much longer than their intended lifetime and typically replace them only when they reach their operational end-of-life. This has significant energy efficiency implications. Through swift action, the replacement rate of old motors by high-efficient ones can be raised significantly , which would offer additional energy savings on top of the savings potential of existing EU regulations, with all the associated benefits.

EU-MORE has conducted a review of existing policies in EU member states that directly or indirectly aim at accelerating motor replacement. A total of 61 policy measures have been identified and analysed for their approach, impact and lessons learnt, leading to an initial set of general observations. These observations will be used to derive policy recommendations.

A first observation is the uneven geographical distribution of the identified measures and their impact. While countries like Germany, Austria, the Netherlands and Poland manage to achieve a relatively substantial impact, other major European economies like Italy, France and Spain have implemented few policies to enhance the replacement rates of motors. A second observation is that support systems of a financial kind, including subsidies, loans and fiscal compensations, comprise the large majority of all policy measures. Whether this kind of measures is still the most effective could be questioned, as the pay-back times of motor replacement have become shorter with rising electricity prices. The lack of information is a major barrier that is much less addressed by existing policy measures. Many of the identified measures were part of wider industrial energy efficiency programmes, in which the benefits of motor replacement were insufficiently clarified. Even when energy efficiency audits do identify motor replacement as a potential action, there are still many barriers to overcome before implementation actually takes place, and these barriers seem to be insufficiently addressed by the existing policies.

Finally, the large majority of the policy measures target industry, while service companies, municipalities and buildings are much less aimed at, despite the abundant presence of motors in those organizations, for example in HVAC systems and elevators.

This paper discusses the analysis of existing policy measures in detail and shine light on policy recommendations derived from this analysis.

ABSTRACT. On December 25, 2020, The Ministry of Economy, Trade and Industry (METI) formulated a “Green Growth Strategy towards 2050 Carbon Neutrality”. And on October 2021, they formulated the “6th Strategic Energy Plan”, this energy policy path was showed for reduction of energy origin GHG (46% reduction in FY 2030 compared to 2013, and 50% higher). The key measure to reduce energy origin GHG are the Electrification, the Decarbonization energy, the Decarbonization of power generation, the Carbon removal. In Japan, approximately 85% of GHG emissions are energy-derived CO2 from the Industrial sector, the Business Division, the Consumer sector, the Transportation Division, the Energy Conversion. As a measure to promote energy conservation on the demand side, the Energy Conservation Law (hereinafter referred as ”ECL”) was revised on April 2023, in addition to the current rationalization of the use of fossil energy, the revised ELC calls for rationalization of the use of all energy, including non-fossil energy, and optimization of electricity demand. And in the Specific energy consumption equipment (top runner system) of ELC, 32 products (AC motor etc) are designated as specified equipment, these are specified in the majority of energy-derived CO2 emissions divisions. It is known that 70% of electricity is used with motor in industrial use. Therefore, in order to achieve Carbon Neutrality, it is important to expand the popularity of high efficiency motors. (1) Trends in the number ratio of top runner motors (IE3 motors) in all motors Since AC motor were designated as specified equipment in April 2015, JEMA continues to investigate the number ratio of top runner motors (IE3 motors), and the results are as follows. FY 2016(64.0%), FY 2017(66.6%), FY 2018(69.1%), FY 2019(72.6%), FY 2020(67.1%), FY 2021(68.6%), FY 2022(73.6%) These results are considered as an effect by ELC. The paper shows one consideration as to why top runner motors (IE3 motors) is expected to be one of the measures that can contribute to a 46% reduction in GHG emissions in 2030 compared to 2013. (2) Next stage Carbon Neutrality is a difficult target to realize, but in the Green Growth Strategy, it is decided to challenge. To achieve Carbon Neutrality by 2050, it will need further study how to even higher efficiency of the motors, and other majeure.

ABSTRACT. The escalating demand for energy-efficient motor-driven systems (EMDS) in industry together with the rapid pace of digitalization presents a significant challenge and opportunity for workforce development. We outline a novel educational approach that harmonizes an educational pathway with the specific digital competencies required for EMDS. We introduce a modular learning framework that integrates short, context-rich learning journeys with the digital skills identified as critical for EMDS, such as data analysis, system design, and optimization techniques. The program is structured using a 'metro line' concept, delivering compact, intensive modules that cover a comprehensive range of topics, from the fundamentals of electric motors to the implementation of advanced control strategies for maintenance engineers and from integrating energy-saving opportunities, regulatory frameworks, and lifecycle cost analysis for management. By embedding the principles of nano-learning and digital badging, we aim to rapidly upskill the workforce in both generic and specialized competencies, as outlined in the REEDS Digital Skills Framework. The curriculum is responsive to industry needs, emphasizing hands-on application through collaborative workshops and real-time data analytics. The ultimate goal is to facilitate a proficient workforce capable of driving EMDS efficiency initiatives within their organizations, thereby advancing both economic and environmental objectives. By combining the novel educational model with industry-specific content, the initiative aims to foster a culture of continuous learning and improvement in the electromechanical systems domain.

ABSTRACT. The finite element analysis (FEM) is a powerful tool applicable to many types of physics. Nowadays is widely used for research and even in industry for designing electrical machines as motors and generators with a high fidelity between model and manufactured machine. In this way, for industrial applications, FEM is considered a shortcut to development. In this context, electrical motors are always looking for high efficiency by increasing the rotational frequency, reducing the active material, increasing the power density, and reducing the footprint. However, evolution also sets constraints for the design, such as for high-speed motors, the bearings, and the resistance of materials. In the case of bearings, could be applied magnetics bearing for industrial applications. In the future is expected the use of a bearingless motor (BM) is to reduce the number of components of the motor and also the total length of the rotor that implies the first critical speed. The concept of BM has been developing over time, mainly in the research area with no large application in industry. This could be explained by the fact that there are three main fields of research in BM: electrical design, control, and power electronics. In this way, it is necessary for a multi-disciplinary team to implement solutions. This paper brings an innovation introducing a FEM-based reduced order model (ROM) for a BM. Until now, no proposal for integration of the three fields has been made in only one model. Usually, the motor is developed in FEM and introduced as an analytic control that does not consider the spatial harmonics and the harmonic saturation between the currents of stator and levitation. The current ROM stator was designed with dual purpose no voltage winding (DPNV) to optimize the size of the frequency inverter on a permanent magnetic motor, therefore, presents the second innovation. Besides there are polyphase ROM, this is the first that uses two independent windings.

ABSTRACT. The automotive industry is in a rapidly transformation process with the in-fluences of the electric mobility and autonomous driving, which has also an impact on the knowledge of developers about the behavior of electric motors. In order to provide an accurate prediction of efficiency of electric motors and condition monitoring, it is essential to precisely determine the torque of an electric motor depending on various influencing factors. In response to this circumstance, this paper presents a methodology for the development of a virtual sensor for torque prediction. According the state of the art, virtual sensors are a good method to handle the challenge for a torque prediction. In order to develop a realistic torque prediction, all possible influencing variables of the electric machine are recorded. In order to eliminate the in-fluences of a test specimen, two asynchronous machines with the identical construction (440 kW nominal power) are braced against each other with a cardan shaft. The electrical machines are equipped with a speed sensor on one side and a torque sensor on the other side of the machine rotor shaft. In order to crystallize an optimal method for developing a virtual sensor, data-driven AI models were created and discussed in comparison to physical models. The results of the individual model approaches are compared with real data and discussed in this paper. The black box model has an optimized accuracy in the area of torque prediction. The significance of this endeavor lies in its potential to revolutionize the field of electric vehicle engineering. Traditional physical sensors have limita-tions in terms of cost, complexity, and scalability. Our proposed virtual sen-sor offers a promising alternative, circumventing these constraints while de-livering a specified torque prediction. This innovation represents a substan-tial step forward in the pursuit of efficient and reliable electric propulsion systems. Furthermore, the discussion and comparison between the physical and black box approach build up a good basement and shows the possibilities of the different methods.

ABSTRACT. This paper describes the process of a successful motor replacement activity for a big steel wire company. In order to achieve its sustainability goals, the company decided to analyze the impact of changing to high efficiency motors (IE4 or IE5) for the installed base of wire drawing machinery. The installed base of over 1000 machines originally contained frequency controlled IE2 and IE3 induction motors. Due to the nature of the driven process, the electric machines are mainly operated in the field weakening region. The paper discusses the different phases in the process, starting from gathering energy efficiency data in the operating region from manufacturers. The validation testing of this data based on motor testing is also reported together with an analysis of the compatibility of the selected high efficiency motors with the original power electronic converter. The motor analysis takes into account induction motors, synchronous reluctance motors and permanent magnet motors. After the technical assessment in terms of the possible energy savings, the economics in terms of pay back are analyzed. The paper also deals with the complexity of the different energy costs in different regions worldwide and the impact on the pay back. In the final part of the paper, the actual roll out of the motor replacement is discussed together with the first field results of the energy measurements.

ABSTRACT. China has established a comprehensive standardization framework for air compres-sors, encompassing both product specification and energy efficiency standards. This paper presents the latest iteration of “GB 19153-2019  Minimum allowable values of energy efficiency and energy efficiency grades for displacement air compressor”[1] (GB19153), elucidating its scope, energy efficiency metrics, classification criteria, and testing parameters. Moreover, this paper delineates China's recent endeavors in enhancing the efficiency standardization of compressed air systems, as articulated in the industry standard" T/CGMA 033001-2018 Guide to Energy Efficiency Classification for Compressed Air Stations." [2] (T/CGMA033001) . This standard proffers a classification scheme for the energy efficiency of compressed air stations within China, exhibiting a dis-cernible 10% variance in efficiency between adjacent grades and a notable 45% discrepancy between Grade 1 and Grade 5. Grade 5's energy efficiency level typifies the average performance of extant compressed air stations in China.Furthermore, a comparative analysis of air compressor minimum energy perfor-mance standard (MEPS) across GB19153, the EU Lot31 proposal "Possible require-ments for compressors for standard air applications DRAFT ECODESIGN REGULATION"[3] (Lot31) , and the US standard "Energy Conservation Program: Energy Conservation Standards for Air Compressors[4]"(ECSAC) is conducted, encompassing facets such as product scope, energy efficiency metrics, tolerance thresholds, testing conditions, and MEPS stipulations.It is recommended that the potential for energy savings in compressed air systems far exceeds that of individual components. As efforts in energy conservation deepen, emphasis will inevitably shift towards enhancing system-wide energy efficiency, particularly concerning the energy conservation of compressed air stations. Interna-tional organizations and societies ought to pay greater attention to promoting the efficiency of compressed air systems.

ABSTRACT. Topic: 7. Refrigeration Systems

In collaboration with EnergieSchweiz (Swiss Federal Office of Energy, SFOE), an investigation was conducted into the energy behavior of compressor types. This led to the development of a compressor tool [4] that evaluates and compares various types of compressors based on application, variable load profiles and locations in terms of seasonal energy efficiency. The core of the tool is a database containing polynomials for over 1400 compressors from different manufacturers. Data was collected for different design points, cooling capacities and refrigerants. Based on the database, 70 neutralized compressor characteristic maps were derived. The characteristic maps show the average behavior (efficiency, application limits, control range) of a compressor type based on the data from multiple manufacturers. A self-defined evaluation method (aCOP) is used to evaluate the seasonal efficiency of the different compressor types based on location, load profile, and application. The evaluation method is based on five energetically weighted operating points. The compressor characteristic maps are utilized to assess operating and control ranges, as well as to determine efficiency at each operating point.

ABSTRACT. Compressed air is a useful energy source but is costly to produce and prepare. A large part of the energy is lost as waste heat during compression. Around 1/3 of it is also lost as leakage during distribution and use. A heat recovery system is the solution for the waste heat and detecting the leakage area is important for the leakage. Another important consideration is knowing the amount of leakage. One problem with leakage elimination is that the pressure in the system must drop to zero, which is costly and only possible if the benefit for elimination is higher. Ultrasonic microphones are often used to detect the leak location, however, they are unreliable in quantifying the leak due to the indirect measurement and the many problems that affect the measurement, such as noise, reflection, distance, and angle to the leak. In this work, we used three different wide-band microphones and measured standard geometries of leaks that we created as circular holes in different sizes to compare these microphones and see how they perform.