The effects of internal heating on gas flow rate measurements using piston provers

V merilniku pretoka plina s pomičnim batom, ki je opremljen z zaščitnim pokrovom, se tudi v stacionarnih temperaturnih razmerah pod pokrovom, zaradi toplotnega toka, ki ga generira merilna elektronika, vzpostavi temperatura, ki je višja od temperature merjenega plina. Ta vpliv povzroči sistematske merilne pogreške merjenega pretoka plina. V nalogi smo zasnovali nov pokrov, ki omogoča prepihovanje merilnega valja z zunanjim izvorom zraka. Zatem smo določili vpliv intenzivnosti prepihovanja na temperaturne razmere v merilniku in na izmerjeni pretok. Ugotovili smo, da tudi ob prepihovanju ne uspemo doseči istih temperaturnih razmer kot pri odprtem merilniku. Med prepihovanjem se relativni pogrešek merjenega pretoka ni ustalil, temperatura merilnega valja pa ostane višja od temperature merjenega plina.In a piston prover equipped with a protective cover, even in stationary temperature conditions a higher temperature than that of the measured gas even is established under the cover due to the heat flux generated by the measuring electronics. This influence causes systematic measurement errors in the measured gas flow. We designed a new cover that allows cooling of the measuring tube with an external air source. We tested the influence of the blowing intensity on the temperature conditions under the cover and on the measured flow. We found that even with blowing, we do not manage to achieve the same temperature conditions as with an open meter. During blowing, the relative error of the measured flow did not stabilize, and the temperature under the hood remains higher than the temperature of the measured gas