The Rider or Compression Engine

animated gif In this type of engine there are two loaded pistons operating 90 deg out of phase. The enclosed working gasses are shifted between the two cylinders passing through the heat exchangers H1 and H2 and the regenerator R.
animated gif

The animation (shown right) shows how the enclosed gasses are compressed (shown blue) or expanded (shown red)

The Rider engine works on a reversible cycle.

If the machine is driven by, say, an electric motor then it will acts as a heat pump or refrigerator. The gasses when shifted from left to right cylinder will be expanded and the temperature falls. The gasses when moved from right to left cylinder will be compressed and the temperature rises. Heat will therefor be absorbed in the right cylinder and given up in the left cylinder. The temperature in H2 falls and rises in H1.

For the machine to act as a motor, heat must be applied to the right cylinder, via H2, and abstracted, by means of a cooler, H1, from the left cylinder. The enclosed gasses will be heated and thus expanded (internal pressure rises) when moved from left to right cylinder, through the heater, H2. When the gasses are moved from right cylinder to the left, they are compressed but the heat of compression is removed by the cooler, H1, so the internal pressure falls.