A novel adsorption air conditioner is designed that supplies 8-12 degrees C chilled water for the fan coil in the locomotive operator cabin. Different from other two-bed adsorption cooling systems, this system has two adsorption/desorption chambers. One adsorber, one condenser and one evaporator are housed in one and the same adsorption/desorption chamber. There are no valves installed in the vacuum side. So, the reliability of the system is improved greatly. This machine uses zeolite and water as the working pairs. This system is driven by 350-450 degrees C exhaust gas generated by the internal combustion engine of the locomotive. The designed refrigerating power and COP (coefficient of performance) are 5 kW and 0.25, respectively, according to the requirements for the refrigeration output in the locomotive operator cabin and the waste heat provided by the engine. In this paper, a model for this system is described, and the simulation results are discussed; The model is validated in principle by limited experimental data. According to the calculation results, the refrigerating power of the machine is up to 10 kW with gas inlet temperature of 450 degrees C and evaporating temperature of 6.5 degrees C. The adsorber can be heated from 97 degrees C to 423 degrees C or cooled from 423 degrees C to 97 degrees C in 1320 s. Therefore, the heat and mass transfer performance of the adsorber is improved greatly. A few experimental data prove these conclusions. (c) 2005 Elsevier Ltd. All rights reserved.