Citation: Dindorf, R.; Takosoglu, J.; Wos, P.Review of Compressed Air Receiver Tanks for Improved Energy Efficiency of Various Pneumatic Systems. Energies 2023, 16, 4153. https://doi.org/10.3390/en16104153 Academic Editor: Jose A. Almendros-Ibanez Received: 19 March 2023 Revised: 29 April 2023 Accepted: 15 May 2023 Published: 17 May 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). energies Review Review of Compressed Air Receiver Tanks for Improved Energy Efficiency of Various Pneumatic Systems Ryszard Dindorf * , Jakub Takosoglu and Piotr Wos Faculty of Mechatronics and Mechanical Engineering, Kielce University of Technology, al. Tysiaclecia Panstwa Polskiego 7, 25-314 Kielce, Poland * Correspondence: dindorf@tu.kielce.pl Abstract: This review examines compressed air receiver tanks (CARTs) for the improved energy efficiency of various pneumatic systems such as compressed air systems (CAS), compressed air energy storage systems (CAESs), pneumatic propulsion systems (PPSs), pneumatic drive systems (PDSs), pneumatic servo drives (PSDs), pneumatic brake systems (PBSs), and compressed air vehicles (CAVs). The basic formulas and energy efficiency indicators used in a CART calculation and selection are included. New scientific research by the authors on measurements based on tank methods, numerical solutions in the process of charging and discharging, the valve-to-tank-to-valve system and pneumatic propulsion system was presented. The numerical model of the valve-tank-valve system takes into account CART polytropic charging and discharging processes, the mass flow balance equation, and the sound (choked) and subsonic mass flow rate in the inlet and outlet valves. Future research directions to improve the energy efficiency of a CART charging and discharge are highlighted. The effective density of energy storage in CART was compared to that of other renewable energy sources and other fuels. Economic and environmental issues were also considered by adopting various energy performance indicators. The discussion also focused on the design concept and computational model of the hybrid tricycle bike (HTB) pneumatic propulsion system. Keywords: compressed air receiver tank; pneumatic systems; energy efficiency; energy storage and recovery; air tank charging and discharge processes 1. Introduction This review deals with both high-pressure and low-pressure pneumatic systems. In high-pressure pneumatic systems, compressed air is usually stored in a tank, with pressures ranging from 100 to 500 bar depending on specific applications. High-pressure pneumatics play an important role in modern manufacturing processes, modern technologies, and energy storage. High-pressure compressed air has many applications, most commonly in air propulsion systems (200 bar), underwater survey activities (450 bar) and air storage in tanks (500 bar). Most applications of low-pressure industrial pneumatic systems use up to 10 bar pressures. In industrial practice, this pressure level is used for operational and economic reasons. The low-pressure pneumatic system is also due to the technical capability of single- stage compressors. These compressors can be stationary or mobile, depending on their intended use. Low-pressure pneumatic systems are compressed air systems (CAS) used in industry, manufacturing, mining, power engineering, road transport, railway, marine and aviation, pneumatic tools, medical equipment, blow-off technology, cleaning, and cooling, etc. [1]. CAS networks are used to transmit and deliver compressed air energy (CAE) to pneumatic equipment (actuators, motors, engines, tools), machinery, and conveyors, etc. Compressed air must be delivered with sufficient capacity, pressure and quality to meet the demand of consumers and ensure the proper operation of pneumatic devices [2]. Incorrectly designed and selected CAS can increase energy costs, cause equipment failures, reduce production efficiency, and increase maintenance requirements [3]. In CAS, there Energies 2023, 16, 4153. https://doi.org/10.3390/en16104153 https://www.mdpi.com/journal/energies