The Journal of Engine Research

The Journal of Engine Research

Experimental evaluation and performance analysis of a bidirectional compressed air engine with a common crankshaft and connecting rods

Document Type : Original Article

Authors
Mehdi Mostaghelchi
Mohammad Omidpanah
Department of Mechanical Engineering, Technical and Vocational University (TVU), Tehran, Iran
10.22034/er.2026.2077052.1116
Abstract
In this paper, a novel engine capable of operating in two modes—as a compressed air engine and as a compressor—is analyzed and investigated. In this configuration, two reciprocating pistons are arranged opposite each other and operate in two separate cylinders. A common connecting rod is also employed in the power transmission mechanism between the crankshaft and the pistons. In the compressed air engine mode, mechanical rotary valves are used to control the fluid flow into the engine, and the power generated by the pistons is transmitted to the common connecting rods and the crankshaft. The engine was first designed; after the stress analysis of its components was verified in software, a prototype was manufactured, and data were then collected and analyzed using sensors and electronic equipment. The results of this research comprise experimental analysis, thermodynamic analysis, and simulation. According to the experimental results obtained from the operation of the mechanism as a power generation engine, the average output speed of the engine at a gauge pressure of 5 bar is 190 rpm, and the engine output power is 870 W. The results obtained from the derived analytical relations, the model solution, the software simulation, and the experimental data also show good agreement and consistency in the engine analysis.
Keywords
Double-Piston Engine
Mechanical Rotary Valve
Common Crankshaft
Bidirectional Compressed Air Engine
Reciprocating Air Engine
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  • Receive Date 23 November 2025
  • Revise Date 04 February 2026
  • Accept Date 04 August 2026