CHEMICAL ENGINEERING TRANSACTIONS VOL. 39, 2014 A publication of The Italian Association of Chemical Engineering www.aidic.it/cet Guest Editors: Petar Sabev Varbanov, Jiří Jaromír Klemeš, Peng Yen Liew, Jun Yow Yong Copyright © 2014, AIDIC Servizi S.r.l., ISBN 978-88-95608-30-3; ISSN 2283-9216 DOI: 10.3303/CET1439026 Please cite this article as: Dizadji N., Rashtchi M., 2014, An experimental investigation of energy saving in air compressors, Chemical Engineering Transactions, 39, 151-156 DOI:10.3303/CET1439026 151 An Experimental Investigation of Energy Saving in Air Compressors Nader Dizadji* a , Maryam Rashtchi b a Department of Mechanical Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran b Research Institute of Petroleum Industry, Tehran, Iran naderdizadji@srbiau.ac.ir According to the literatures, compressed-air systems account for about 10 % of total industrial-energy use for few countries. Compressed air is typically one of the most expensive utilities in an industrial facility. These compressors are ordinarily driven by constant-speed electrical motors supporting varying load conditions; i.e., substantial energy is lost since the loading conditions mismatch the designed optimal energy consumption needs of the desired purpose. In this paper, the electric energy consumption of one-cylinder reciprocating air compressors has been experimentally investigated, once by the use of variable speed drive (VSD) and then by the use of mechanical speed drive. Based on the experiment, the reduction of energy consumption in various compressors' discharge pressures falls between 43.6 % and 60.5 %. The results indicate that the use of a variable speed drive reduces electrical energy consumption and thus reduces greenhouse gas emissions due to the reduction of fossil fuel consumption. 1. Introduction Due to the constraints of fossil fuels and the environmental problems caused by the combustion of them, the necessity of energy management and enhancing the energy efficiency has been more evident than ever, especially in countries where producing electrical energy is dependent on these fuels. Energy dissipation of devices leads to climate change and eventually global warming which is the major problem for earth and its lovers (Jayamaha, 2006). Electrical energy consumption in Iran has increased approximately from 2,220 GWh to 100,000 GWh, through the years 1976 to 2000. In Iran, about 50 percent of total energy is used to drive industrial motors (Massarrat, 2004). Optimal energy use is fulfilled when less energy is consumed to deliver a service or, when more services are delivered by the same amount of energy (Järvinen, 2013). Industrial units will consume more energy than other units (Abdelaziz et al., 2011). Air compressors are one of the most high-cost utilities among the industrial units and take about 10 % of the industry’s total energy. Compressed air manufacturers in the US account for ten percent of the total electricity used in all industries (Senniappan, 2004). At least one type of compressor is used in 70 % of America's manufacturing industries (Xenergy Inc., 2013). In Europe (Saidur et al, 2011) and Africa (Marais, 2009), respectively, 10 and 9 % of industrial electricity consumption is devoted to air compressors. In Malaysia, 10 % of industrial electricity consumption is devoted to air compressors (Saidur et al, 2011). Therefore, any effective action towards improving the energy efficiency of the compressors is highly attended by researchers, policy makers and manufacturers. Several measures towards reducing compressors energy consumption, such as application of high- performance engines, application of VSD, prevention of leakage, reducing pressure drop, and application of efficient nozzles in compressors system have been reported (Abdelaziz et al., 2011). Data auditing was employed to estimate the energy use of the boiler fan motors. VSD was also used to estimate energy savings by modulating fan speed. It was found that 139,412 MWh, 268,866 MWh,