Proceedings PaperOn the efficiency of heat engines by pulsed laser
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The purpose of this paper is to present a possibility of improving the efficiency of light driven actuators by using pulsed laser and to investigate theoretical limit of its efficiency, thereby providing an insight for the design of an efficient light driven actuator in the future. Many light driven actuators based on the heat deposit can be regarded as heat engines, and consequently their efficiencies are subjected to the limitation from Carnot's theory, which dictates that the maximum efficiency is larger for larger temperature difference between the high- and the low-temperature reservoirs. If one uses focused laser pulses, an extremely high temperature difference can be created for a short fraction of time, therefore, there is a possibility of achieving a higher efficiency. In the theoretical treatment, a cycle in which heat is given instantaneously in an adiabatic condition was considered. The formula for the maximum efficiency was derived, which gives about the half that of Carnot cycle efficiency at an ambient temperature of 300K. In an ideal case, for the instantaneous temperature increase of 200K the maximum efficiency can be about 20 %.