Tomohide NISHINO Kenichi KATO Kimiko IMAI Hiroyuki KATO

Transcription

1 Tomohide NISIN Kenichi KAT Kimiko IMAI iroyuki KAT Kazuhiro FUKUMT With regard to the desire for more passenger comfort there is a specia need for an efficient deodorant fiter. Since customers are becoming so sensitive about cabin odor, the deveopment of a more effective deodorant fiter is strongy required. utside of the vehice, diese odor is the most obnoxious, therefore, anaysis of this diese gas and the conducting of an investigation to identity the main ingredient responsibe for the strong odor were executed. Acetadehyde gas was estabished as the main cuprit. Therefore, identification of a chemica that coud be impregnated in activated carbon and adsorb acetadehyde gas was required, since activated carbon itsef does not have the abiity to adsorb acetadehyde gas. Finay vitamin Bx was found to be the appropriate chemica. At the end of this report, a sensory evauation resut by twenty paneists with regard to deodorant type cabin air fiters impregnated with vitamin Bx and their efficiency in fitering wi be deivered. Key words : Deodorant fiter, Diese odor, Acetadehyde gas, Air Refiner is our product name for the air conditioner fiter of a vehice, which serves to purify cabin air, and is assembed in the air conditioning system (). From the interior From the exterior Air Refiner Air conditioning system Fig. 1 Air Refiner and air conditioning system The Air Refiner ceans the air coming in from outside and introduces cean air into the cabin, therefore, keeping the airfow resistance ow is necessary for it not to have an adverse affect on the air conditioning quaity. The critica points regarding the air refiner s deveopment are maintainment of high quaity and ow pressure. The dust removing mechanism can be divided into the physica fitration type and eectrostatic fitration type. The physica fitration type physicay captures the dust empoying fiber, and is highy efficient visàvis reativey arge partices of micron size, whie inefficient with regard to smaer partices of submicron size (). The eectrostatic fitration type is inefficient visàvis reativey arge partices because of powerfu inertia force, but is highy efficient with regard to smaer partices of submicron size, because this type of fiter is capabe of capturing the dust utiizing Couomb force with eectrostatic fiber (). We have three types of dust adsorbing fiters, namey, the arge partices type, ong ife type and high efficiency type. The arge partices type is pure fabric and has the advantage of a high airfow rate due to ow pressure, and the ong ife type has the abiity to essen rising airfow resistance because it is ightweight and its eectret quaities are high. The high efficiency type is highy efficient regarding both arge and sma partices (as its name suggests), but the pressure is high and aso easiy accumuate dust. Recenty, customers are getting more sensitive regarding unpeasant odors, and the deveopment of a more effective deodorant fiter is required. Therefore, in order to define the target it is necessary to judge whether a certain odor is acceptabe or not, and to deveop a deodorant fiter based

2 Submicron size Micron size Diese gas Gas chromatography Virus Diese soot Samping Gas concentration: S Diese smoke Tobacco smoke Earth dust, cement Fungi Poen Partice size ( µ m) Threshod: So dor S dorconcentration: S/So S/So1 : unabe to sense the odor S/So1 : abe to sense the odor Fig. 2 Types of environmenta dust Fig. 4 Diese gases anaysis procedure Dust Fiber Fig. 3 Dust removing methods of eectrostatic type on that judgment. The main cause of unpeasant odors in the cabin is diese odor entering from outside of the vehice. Because of this, an investigation was conducted into diese and the deveopment of a deodorant fiter to eiminate diese odor was initiated, and the procedure undertaken is outined in the foowing chapters. First of a, a diese gas anaysis was conducted (). Some sampes of diese gas were obtained, and the constituents of the diese gas were measured empoying gas chromatography. S represents gas concentration, and S 0 represents the threshod. If S/S 01, man is not abe to sense any odor, however if S/S 01, man is abe to sense the odor. Pease refer to the anaysis resut of diese odor. ny Acetadehyde was S/S 01, the remainder were S/S 01. By cacuating the resut from this formua, we can see that acetadehyde is the cause of strong diese odor. Therefore, it is necessary to deveop a deodorant fiter to remove acetadehyde in particuar. The ingredient of diese Acidic odors Neutra odors Adehydes type Inorganic compound Carbohydrate Acetadehyde Formadehyde Acroein No 2 So 2 Akane type So (ppb) nbutane Aromatic carbohydrate 370 Fig. 5 Anaysis resut of diese odor 4 [So : Threshod S : Gas concentration] S (ppb) S/So Generay, deodorizing is conducted through gas adsorption empoying activated carbon, and the gas adsorption is divided into physica adsorption and chemica adsorption ( ). Activated carbon is porous in nature (micropores, macropores), and the specific surface area ranges over 1000 m 2 /g. Physica adsorption represents a mechanism whereby the odor moecues are captured within the pores. Physica adsorption is efficient with regard to neutra gases, such as touene and butane, but is not very efficient visàvis strong poarity gases, such as adehyde and ammonia. Accordingy, the surface of activated carbon is impregnated with chemicas, and the impregnated activated carbon is abe to capture poarity gases through a chemica reaction (chemica adsorption), e.g. impregnated activated carbon with acidic agent carboxyic acid has an effect on the basic gases such as ammonia, and impregnated activated carbon with basic agents incuding the amino group has an effect on the acidic gases such as acetadehyde. Therefore, impregnated activated carbon containing the Target gas; Acetadehyde

3 N C NC R R Basic gases Chemica adsorption Surface of activated carbon Neutra gases RC (Carboxyic acid) Physica adsorption C 3 C NRC 3 CNR R R Acidic gases Fig. 6 Deodorant mechanism Chemica adsorption RN 2 (Amino acid) Aromatic amino group chemica adsorption C 3 C N RC 3 C NR s chemica adsorption C 3 C X : Acetadehyde after reaction and phosphoric acid X C 3 C and phosphoric acid Poymer and phosphoric acid Fig. 7 Chemica adsorption of acetadehyde X n C 3 C amino group is a necessity for the adsorbtion of acetadehyde, At the beginning of the study, the aromatic amino group was tested, however, the impregnated activated carbon with the aromatic amino group exhibited poor deodorizing performance. ver a ong period, its efficiency decreased, necessitating the discovery of a more suitabe materia that woud enabe a greater deodorant efficiency in the adsorption of acetadehyde over a onger period. and phosphoric acid were chosen to fit this requirement. is a safe materia that can be found in yeast and spinach etc., and whose chemica name is paraamino benzoic acid. Using vitamin Bx by itsef did not react to acetadehyde, however, a combination of vitamin Bx and phosphoric acid, which formed acid sat, had a dramatic effect on the adehyde gases. Normay, one moecue of the aromatic amino group chemicay bonds to ony one moecue of acetadehyde. n the other hand, one combined moecue of vitamin Bx and phosphoric acid enabed chemica bonding to mutipe moecues of acetadehyde, and formed synthesized poymer (). Therefore, the impregnated activated carbon with vitamin Bx and phosphoric acid wi adsorb acetadehyde more effectivey than current impregnated fiters empoying the aromatic amino group. both, visàvis acetadehyde was conducted. Activated carbon was impregnated with vitamin Bx and phosphoric acid for the vitamin Bx fiter, and activated carbon was impregnated with the aromatic amino group for the current fiter. The picture and structure of the deodorant fiter used for the test is shown in. The fiter size, mass and type of activated carbon are the same. The efficiency and Eectret paper Impregnated activated carbon An experiment to compare a fiter impregnated with vitamin Bx with a current fiter (impregnated with aromatic amino group) to compare the adsorption performance of Cover Cross section of fiter medium Fig. 8 The picture and structure of deodorant fiter

4 capacity of the fiter were measured with the test equipment (). Acetadehyde gas used for evauation was a diuted acetadehyde soution with air. Acetadehyde gas was measured empoying gas chromatography. The airfow veocity of the fiter was 1.4 m/s. Gas chromatography Stainess box (2.5m 3 ) Acetadehyde gas Fan η 0 : natura damping ratio (%) The anaysis method used for the adsorption capacity of the fiter was conducted as foows. (1) After the above items (1) and (2) of Anaysis method of fiter efficiency were conducted, fiter adsorption capacity was cacuated using the Fiter Adsorption Capacity Formua. WM*V/(22.4*(273T)/273)*C 0*(ηη 0) Bower unit Fiter Power source Fig. 9 Test equipment The anaysis method used for the adsorption efficiency of the fiter was as foows. (1) Pace a bower unit with no fiter into a stainess box. Adjust acetadehyde concentration in the stainess box to 3 ppm, and operate the bower unit for 30 minutes. The natura damping ratio is measured by this method, and the formua for η 0 is 1(acetadehyde concentration after 30 minutes operation/ acetadehyde concentration at the outset). (2) Pace bower unit with fiter into a stainess box. Adjust acetadehyde concentration in the stainess box to 3 ppm, and operate the bower unit for 30 minutes. Whie operating the bower unit, measure acetadehyde concentration in the stainess box severa times. (3) Fiter adsorption efficiency is cacuated at t1 by foowing the Fiter Adsorption Efficiency Formua. η n (C 0 /(C t C 0*h 0 *t/30))/t*v /Q η : fiter adsorption efficiency (%) C 0 : gas concentration at the outset (ppm) C t t : gas concentration after t minutes (ppm) : time (min) V : voume of box (m 3 ) Q : air fow voume (m 3 /min) W : fiter adsorption capacity (mg) M : moecuar weight of gas V : voume of box (m 3 ) T : temperature (ºC) C 0 : gas concentration at the outset (ppm) η : concentration damping ratio at 30 minutes (%) η 0 : natura damping ratio (%) (2) Item (2) of Anaysis method of fiter efficiency above is repeated unti ηη 0, when concentration damping ratio became equa to natura damping ratio (unti the imit of the fiter capacity), and tota fiter adsorption capacity (fu fiter ife capacity) is cacuated. The reationship between fiter efficiency and fiter capacity of acetadehyde gas is shown in. As you can see from that, the vitamin Bx fiter adsorbs 3 times or more acetadehyde than the current fiter. shows the reationship between fiter efficiency and the quantity of acetadehyde that passed through the fiter. At first gance, it is cear that the period of efficiency regarding acetadehyde adsorption of vitamin Bx fiter is much onger than the current fiter. The vitamin Bx fiter maintains exceent efficiency visàvis acetadehyde adsorption.

5 100 Vehice 1 Vehice 2 Efficiency (%) Current fiter Front 12m Rear 0 0 Tota capacity Fig. 10 Deodorant quaity regarding acetadehyde (1) 100 Efficiency (%) The amount of acetadehyde passage to fiter (mg) Current fiter Fig. 11 Deodorant quaity regarding acetadehyde (2) Regarding the deodorization effect, in a aboratory experiment it was estabished that the vitamin Bx fiter is superior to the current fiter. Then it became necessary to aso prove that the vitamin Bx fiter exces in performance over the current fiter in an actua environment. Firsty, a vitamin Bx fiter and a current fiter were prepared. Each of these fiter s size and activated carbon quantity were adjusted to be equa. The fiters were fitted into the air conditioner of a vehice, and were used as an air refiner. Sense evauation for diese odor was conducted at mieages of 1,000 km, 5,000 km and 10,000 km. shows the sense evauation method. Vehice 1 is a diese car, and Vehice 2 is situated one to two meters behind vehice 1. During one minute iding of Vehice 1, paneists in Vehice 2 began sniffing the cabin air, and ranked the odor based on. shows the resut of sense evauation, aso the reationship between the eve of sense evauation for odor and odometer of a vehice where a fiter had been affixed. As for the vitamin Bx fiter, the resut shows that the deodorizing efficiency regarding diese odor of the fiter continues onger than for that of the current fiter. Vehice 1Diese car. Ide Vehice 1for about one minute. Vehice 2Fiter is instaed in air conditioner of Vehice 2. Air fow strength of air conditioner is medium. During iding of Vehice 1, paneists take a sniff and order based on Fig.13. Fig. 12 Sense evauation method Therefore, the activated carbon fiter impregnated with vitamin Bx and phosphoric acid is the best deodorant fiter for diese gases. Sense evauation eve for odor : stronger odor 4 : strong odor 3 : odor easiy sensed (by paneist) 2 : what type of odor sensed (by paneist) 1 : odor barey sensed 0 : no odor Fig. 13 dor intensity rank No odor dometer of vehice (km) Current fiter Fig. 14 Resut of sense evauation Strong odor The deodorant fiter has been deveoped focusing on diese odor during this experiment. The deodorant fiter exhibits efficiency not ony in the aboratory but aso in an actua environment. Now, improvement regarding the quaity of the deodorant fiter is our new target for further deveopment.

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