NDIR gas sensor for spatial monitoring of carbon dioxide concentrations in naturally ventilated livestock buildings

摘要

The tracer gas ratio method, using CO2 as natural tracer, has been suggested as apragmatic option to measure emissions from naturally ventilated (NV) barns without theneed to directly estimate the ventilation rate. The aim of this research was to assess theperformance of a low-cost Non-Dispersive Infra-Red (NDIR) sensor for intensive spatialfield monitoring of CO2 concentrations in a NV dairy cow house. This was achieved bycomparing NDIR sensors with two commonly applied methods, a Photo-AcousticSpectroscope (PAS) Gas Monitor and an Open-Path laser (OP-laser). First, calibrations forthe NDIR sensors were obtained in the laboratory. Then, the NDIR sensors were placed ina dairy cow barn for comparison with the PAS and OP-laser methods. The mainconclusions were: (a) in order to represent the overall barn CO2 concentration of the dairycow barn, the number of NDIR sensors to be accounted for average concentrationcalculation was dependent on barn length and on barn area occupation; and (b) the NDIRCO2 sensors are suitable for multi-point monitoring of CO2 concentrations in NV livestockbarns, being a feasible alternative for the PAS and the OP-laser methods to monitorsingle-point or averaged spatial CO2 concentrations in livestock barns.