Pressure drop in packed beds of spherical particles at ambient and elevated air temperatures

Abstract

The aim of this work was the experimental investigation of the particle friction factor for air flow through a packed bed of particles at ambient and elevated temperatures. The experiments were performed by measuring the pressure drop across the packed bed, heated to the desired temperature by hot air. Glass spherical particles of seven different diameters were used. The temperature range of the air flowing through the packed bed was from 20 to 350°C and the bed voidages were from 0.3574 to 0.4303. The obtained results were correlated using a number of available literature correlations. The overall best fit of all of the experimental data was obtained using the Ergun equation, with mean absolute deviation of 10.90%. Ergun's equation gave somewhat better results in correlating the data at ambient temperature with mean absolute deviation of 9.77%, while correlation of the data at elevated temperatures gave mean absolute deviation of 12.38%. The vast majority of the correlations used gave better results when applied to ambient temperature data than to the data at elevated temperatures. Based on the results obtained, the Ergun equation is proposed for friction factor calculation both at ambient and at elevated temperatures.

Cilj ovog rada je bio eksperimentalno ispitivanje koeficijenta trenja fluid-čestice prilikom strujanja vazduha kroz pakovani sloj čestica, na sobnoj i povišenim temperaturama. Izvršeno je eksperimentalno merenje pada pritiska u pakovanim slojevima različitih temperatura zagrejanih korišćenjem vrelog vazduha. Kao materijal za pakovanje korišćene su sferične staklene kuglice 7 različitih prečnika. Temperaturni interval u kom su vršeni eksperimenti bio je od 20 do 350°C, dok su poroznosti sloja iznosile od 0,3574 do 0,4303. Dobijeni rezultati korelisani su korišćenjem većeg broja literaturnih korelacija. Najbolje slaganje sa eksperimentalnim podacima pokazala je Ergunova jednačina [1], sa srednjim procentnim odstupanjem od 10,90%. Ergunova jednačina je dala bolje rezultate prilikom korelisanja podataka na sobnoj temperaturi (srednja procentna greška 9,77%), dok je korelisanje podataka na povišenim temperaturama izvršeno sa greškom od 12,38%. Većina testiranih literaturnih korelacija je dala bolje rezultate pri korelisanju podataka dobijenih na sobnoj temperaturi u odnosu na podatke dobijene na povišenim temperaturama. Na osnovu dobijenih rezultata, predlaže se korišćenje Ergunove jednačine za izračunavanje koeficijenta trenja fluid-čestice kako na sobnoj, tako i na povišenim temperaturama.