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Indicator Diagram

Heat Engine

An indicator diagram is a chart used to measure the thermal, or cylinder, performance of reciprocating steam and internal combustion engines and compressors. It plots the pressure inside the cylinder against the volume swept by the piston through the two or four strokes that make up one working cycle, producing a closed loop whose enclosed area represents the work done in that cycle. Engineers use the diagram to calculate the work done and the power produced by an engine cylinder, or the work consumed by a compressor cylinder, making it a longstanding diagnostic tool for reciprocating heat engines. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/

Facts
Technology Type
Chart recording cylinder pressure against piston volume to measure steam or combustion engine performance 1
Invented Year
1796 1
Classification
Maturity
TRL 9: Actual System Proven in Operational Environment 1
Sources
1. Wikipedia: Indicator diagram
  • Lead section
    An indicator diagram is a chart used to measure the thermal, or cylinder, performance of reciprocating steam and internal combustion engines and compressors.
  • History section
    In 1796, Southern developed the simple, but critical, technique to generate the diagram by fixing a board so as to move with the piston, thereby tracing the "volume" axis, while a pencil, attached to a pressure gauge, moved at right angles to the piston, tracing "pressure".
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