A NEW VERSION OF H-D DIAGRAM FOR HUMID AIR: THE CONSTRUCTION OF THE CONSTANT - QUALITY LINES IN THE MIST ZONE

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1 Bulletin of the Trnsilni Uniersity of Brşo Vol. 2 (51) Series I: Engineering Sciences A NEW VERSION OF H-D DIAGRAM FOR HUMID AIR: THE CONSTRUCTION OF THE CONSTANT - QUALITY LINES IN THE MIST ZONE D. ŞOVA 1 W. LAURENZI 2 Abstrct: The pper presents the reltionships for the construction of h- igr for hui ir consiering in ition new equtions for the construction of the constnt qulity cures n the constnt- olue lines in the ist zone of hui ir. For the grphicl representtion of h- igr, the progr clle H- DIAGRAM ws eelope. Key wors: hui ir, h- igr, ist zone. 1. Introuction The h- igr for hui ir is useful tool for the eterintion of the specific preters of hui ir uring processes like ir-conitioning or rying. The Mollier igr, o clle the h- (or h-x) igr, is bse on the reltionship between het content (enthlpy) n wter por content of ir. [1] The igr coprises two oins corresponing to unsturte hui ir n hui ir in stte of ist, seprte by borerline which is the sturtion cure. Since the ost processes re stuie in the region of unsturte ir, lesser interest ws pi to the stuy of the ist zone n to the processes eelope in this zone, such s cooling or rying in close circuit. 2. The Construction of H- Digr The h- igr is constructe for the tospheric pressure p =1br. The network of isotherl lines in the oin of unsturte hui ir is plotte on the bsis of the following reltion: h = c t 0 p ( r c t) where: h is the enthlpy of unsturte kj kg, t - teperture p (1) hui ir [ ] [ 0 90 C], - the oisture content of hui ir [ 0 50g kg], r0 - het of poriztion [ kj kg], c p - constntpressure specific het of ir [ kj kgk ], c p - constnt - pressure specific het of wter por [ kgk ] kj. The construction of the network of constnt - reltie huiity cures, ϕ = 0.1 1, is e using the eqution: ( t) p ( t) p ϕ ps = 622 = 622 (2) p p p ϕ where: p is the prtil pressure of the s 1 Dept. of Theroynics n Flui Mechncis, Trnsilni Uniersity of Brşo. 2 Dept. of Mchines for Woo Inustry, Trnsilni Uniersity of Brşo.

2 128 Bulletin of the Trnsilni Uniersity of Brşo Vol. 2 (51) Series I wter por [ br ], ϕ - the reltie huiity, p s ( t) - the sturtion pressure t gien teperture of ir [ br ]. The constnt - olue lines in the zone of unsturte hui ir re represente ccoring to the next reltion: = 622 RT = 622 p (3) where: is the specific olue of hui ir, equl to the specific olue of ry ir [ kg] 3, R - the gs constnt of ir [ J kgk ]. The line of the prtil pressure of wter por is bse on eqution: p p = (4) 622 The prt of the igr situte below the sturtion cure correspons to ixture fore of ry ir n oisture, which is hel by ir in for of por n tiny roplets of liqui t sturtion (wet por). It represents the ist zone. The network of isotherl lines in the ist zone is constructe on the bsis of reltion: ( r c t) c t h = c pt p pl 0 (5) where: is the oisture content of ir in for of ry sturte por t teperture t [ g kg], - the oisture content of ir in for of sturte liqui t the se teperture [ g kg], c pl - the constnt - pressure specific het of liqui wter [ kj kgk ]. The construction of the constnt - qulity cures in the ist zone is perfore ccoring to the following equtions: x oist. = = 1 ps = 622 x p 1 = x ( t) p ( t) s = (6) where: is the oisture content of the hui ir in the ist zone t teperture t [ g kg], oist. - the ss of oisture (por n liqui t sturtion) [ kg ], - the ss of ry ir [ kg ], - the ss of sturte por t teperture t [ kg ], - the ss of sturte liqui t teperture t [ kg ], x the qulity of wet por. Fro its efinition, the qulity of wet por is clculte fro: x =.(7) Bse on eqution (6), the oisture content of hui ir in the ist stte, corresponing to teperture t, cn be eterine for certin lue of the por qulity. For x = 1, we he = ; this ens tht this constnt - qulity cure coincies with the xiu reltie huiity cure ϕ =1. For the qulity lues x < 1, the intersection points of the oisture content lines with the isotherl lines t will be situte on cures plce in the ist zone of h- igr. The constnt - qulity cures perit the eterintion of the stte of wet por for ech point fro the ist zone n o the expression of the preters of hui ir in the ist stte, such s specific olue, ensity or specific het. The construction of the constnt-olue lines in the ist zone is e using the reltion:

3 D. ŞOVA et l: A New Version of H- Digr for Hui Air: The Construction of the 129 V V = x) = x) which cn be o written in the for: R T 622 x p 622 = = x) (8) = (9) where: is the specific olue of sturte liqui [ kg] 3. Eqution (8) ws eterine with the consiertion tht the ss of wet por is: = (10) n the olue of hui ir in the ist stte is: V = V V (11) since in the ixture ir - wet por, V = V. The constnt - olue lines in the ist zone re represente in prolongtion to the constnt - olue lines fro the zone of unsturte hui ir. The enthlpy of hui ir in the ist stte cn be o eterine with respect to the qulity of wet por s: ( r c t) x h = cpt p 0 (12) x) cplt since: = = x (13) The equtions of the stte properties of hui ir he been eterine with the ssuptions tht ir n sturte por re iel gses n the quntities re relte to hui ir tht contins one kilogr of ry ir. 3. The Representtion of H- Digr For the grphicl representtion of h- igr for hui ir, the progr clle H- DIAGRAM ws eelope. It is bse on the equtions inicte in the preious chpter. The grphicl representtion is ccoplishe through the siultion of these equtions. H- igr coprises the following lines: isotherl lines in the zone of unsturte hui ir; constnt - reltie huiity cures; isotherl lines in the ist zone of hui ir; the por prtil pressure line; specific olue lines in the zone of unsturte hui ir; the constnt - qulity lines of wet por; specific olue lines in the ist zone of hui ir; constnt - enthlpy lines. These lines cn be represente either on the se igr (Fig.2) or inepenent (Fig. 4, 7, 8, 10) or groupe ccoring to ifferent criteri (Fig. 3, 5, 6, 9, 11). The progr cn be iproe in orer to eterine preter lue of hui ir with respect to the isplye grph n the position of the cursor on the grph. 4. Conclusions H- igr for hui ir coplete with the constnt-qulity cures n the constnt-olue lines constructe in the ist zone llows the eterintion of the por qulity for ech point of this zone in

4 130 Bulletin of the Trnsilni Uniersity of Brşo Vol. 2 (51) Series I Fig. 1. The in enu of the H- igr progr Fig. 3. Isotherl lines in the zone of unsturte hui ir Fig. 2. The h - igr respect with the oisture content of hui ir. Thus, the stte of por in the hui ir is ore precisely specifie. Fig. 4. Reltie huiity lines

5 D. ŞOVA et l: A New Version of H- Digr for Hui Air: The Construction of the 131 Fig. 5. Isotherl lines in the ist zone of hui ir Fig. 7. The por prtil pressure line Fig. 6. Specific olue lines in the zone of unsturte hui ir Fig. 8. Constnt - qulity lines of wet por

6 132 Bulletin of the Trnsilni Uniersity of Brşo Vol. 2 (51) Series I Fig. 9. Specific olue lines in the ist zone of hui ir Fig. 11. Isotherl lines in the zone of unsturte n in the ist zone of hui ir References 1. oll1.ht. 2. Ržnjeić, K.: Tbele şi igre teroinice. Bucureşti. Eitur Tehnică, Shets, I.T., Tolubinsky, V.I., Kirkoky, N.F., Neuzhy, I.A., Sheluko, I.M.: Het Engineering. Moscow. MIR Publishers, Şo, M., Şo, V., Şo, D.: Soe Consiertions Concerning the Construction n Appliction of the h- Digr for Hui Air in the Mist Zone. In: Bulletin of the Trnsilni Uniersity of Brşo, Vol. XXXV, Series A, 1993, p Fig. 10. Constnt enthlpy lines