Small gas-fired twin pulse combustors with two aerodynamic valves for residential heating appliances were developed. These pulse combustors were designed as a source of space heating, as in combustion-aided heat pump cycles. As a first step, an experimental setup (Phase 1) was built to study conditions for anti-phase operation and to determine a mixing mode between fuel and air. Based on the Phase 1 data, a combustor (Phase 2) was constructed with the help of a computer simulation using a Helmholtz resonator model, which allowed effective combustor design. A premixed injection system was selected for the combustor, which resulted in better stability of the anti-phase operating mode between the two combustion chambers. Also, this combustor, which is two-thirds the size of conventional combustors, shows NOx emission characteristics of less than 25 ppm and a high thermal efficiency of more than 93% over a wide turndown ratio from 3,750 to 20,500 Btu/h (1,100 to 6,000 W). It is shown that twin valveless pulse combustors have the potential of being compact and efficient combustion systems over a wide turndown ratio for residential use without noise or durability problems.

KEYWORDS: gas fired, pulsed combustion, space heating, domestic, experiment, mixing, air, calculating, designing, combustion chambers, nitrogen oxides, efficiency, noise, durability