Could a vortex engine operate using ambient air without a heat exchanger or a heat source?
YES. The air in the boundary layer close to the earth’s surface often has enough heat content (temperature) or moisture content (mixing ratio) to become buoyant when raised. The ability to produce work is called Convective Available Potential Energy (CAPE). CAPE is routinely calculated for every atmospheric sounding. CAPE is measured in Joules per kilogram (J/kg). The CAPE of maritime tropical air is typically between 800 and 1800 J/kg. The CAPE of continental air during periods of heavy insolation can be as high as 5000 J/kg. The CAPE of continental air that has been cooled by radiation early in the morning is usually negative. A CAPE of 1000 J/kg coresponds to a velocity of 45 m/s; a CAPE of 5000 m/s corresponds to a velocity of 100 m/s. Increasing the heat content of surface air by increasing either its temperature or its mixing ratio increases CAPE. The heating of the atmosphere from the bottom by solar radiation tends to increase CAPE. Upward heat convection tends to reduce CAPE a
