| 摘要 |
A flow meter 200 comprises heating means 203 is for heating a fluid flow 202 along a membrane 201 and a temperature difference,ΔT, is measured between and upstream point Tup and a downstream point Tdown—There are additionally provided strips of material having a relatively high heat conductivity 204, 205. The pair of strips 204, substantially perpendicular to the flow direction 202 direct heat from the heater 203 to the sides of the membrane 201. As these strip(s) 204 have a relatively large heat conductivity, a large proportion of the heat that would otherwise drive heat flows 111, 112 is dispersed and does not therefore cause inaccuracies or bias in the measured flow rate. Additionally, a strip of material 205 having high heat conductivity relative to the membrane 201 is provided parallel to the flow direction 202. This acts to direct heat from the heater along the direction of flow. This increases the proportion of heat that flows along this axis and guides the flow 114 and hence reduces the proportion of heat available to drive heat flows 111 and 112 which cause inaccuracies and bias in the measured flow rates
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