Prototype heat exchange and monitoring system at a municipal solid waste landfill in China.

A prototype heat exchange and monitoring system was installed and operated in a newly filled municipal solid waste (MSW) landfill, located in Wuxi City, China. In this study, a test was conducted using the system to investigate the influence of heat exchange on waste temperature over three heat exchange stages. During the period of sharp increase of waste temperature, the first stage test was performed, whereas during the period of gradual increase of waste temperature, the second and third stages were performed. The results showed that (1) the waste temperature increased during the first two months after the commencement of temperature observations. This increase in temperature partially counteracted the effect of the heat exchange system on waste temperature during the first stage test. (2) During the subsequent 360 days, the waste temperature increased gradually. The influence of the heat exchange system was relatively more effective during the second and third stages than during the first stage. (3) During the test, the waste temperatures showed similar changes throughout the saturated portion of the waste, which was below the leachate level. (4) At ten days after the third heat exchange stage, the waste temperature increased gradually to the previous elevated temperature. The results of the test demonstrate that waste temperatures are mainly affected by thermal conduction in the waste mass and thermal convection in the leachate. Moreover, preliminary suggestions are provided for the installation of heat exchange pipes in landfills.