Davlumbazda enerji veriminin arttırılması
Increasing the efficiency of range hood
Yazar: DEHA GÜLŞEN
Danışman: PROF. DR. SEYHAN ONBAŞIOĞLU
İstanbul Teknik Üniversitesi / Enerji Enstitüsü / Enerji Bilim ve Teknoloji Ana Bilim Dalı
Derece: Yüksek Lisans, 2016
Konu: Makine Mühendisliği = Mechanical Engineering

Özet:
Son yıllarda diğer sektörlerde olduğu gibi beyaz eşya sektöründe de enerji verimliliği değerleri ön plana çıkmaktadır. Buna kullanıcıların satın aldıkları ürünlerin enerji tüketimlerine gösterdikleri ilginin yanı sıra, standart kuruluşların beyaz eşya sektörü için getirmiş oldukları deklarasyon zorunlulukları ve belirledikleri kısıtlar neden olmaktadır. Tez çalışması kapsamında da buradan yola çıkılarak özellikle rekabetin üst seviyelere yaklaştığı ve enerji verimliliğinin iyileştirilebilmesi için detaylı çaışmaların gerektiği davlumbaz ürününün enerji veriminin iyileştirilmesi hedeflenmiştir. 
Tez çalışması, mevcut durumda A enerji sınıfı olan perimetralli ve 90 cm olan bir ürün üzerinde gerçekleştirilmiştir. Çalışmada perimetralli bir ürün seçilmesinin sebebi, özellikle hava perdesi oluşturarak yemek buharı toplama ve koku giderim faktörünü arttırmaya yarayan perimetral yapısının optimize edilerek davlumbazın enerji verimliliği değerinin iyileştirilebileceğinin düşünülmesidir. Bu yüzden perimetral tasarımının optimizasyonu için kritik parametrelerin belirlendiği bir tasarım metodolojisi oluşturulmuştur.
Çalışma kapsamında davlumbazda parçalı perimetral yapısına geçişin emiş bölgesindeki akış hızlarının karakteristiğine ve davlumbazın debi değerine olan etkisi sayısal ve deneysel olarak analiz edilmiştir. Sayısal analiz için parçalı perimetralde ortaya çıkan perimetral aralıklarının genişliği ve perimetral aralıklarının konumu, hava debisi ve emiş bölgesindeki akış hızları gibi parametreler dikkate alınmıştır. Hesaplamalı akışkanlar dinamiği analizi için ANSYS Fluent paket programı kullanılmıştır. 
HAD analizlerini doğrulamak için rüzgar tünelinde debi ölçümleri yapılmış ve sayısal sonuçlar ilk durum ve parçalı perimetral geometrisi için %1,54 olan rüzgar tüneli belirsizliği içerisinde kalarak doğrulanmıştır. Daha sonra doğrulanmış analiz sonuçlarına göre parçalı perimetral optmizasyonu için %3 ile %9 arasında hata payı veren, debi ve emiş bölgesi köşelerindeki akış hızına bağlı 2 adet denklem elde edilmiştir.

Abstract:
In recent years, the energy efficiency has come into prominence for white goods manufacturers because of imposing declaration requirement by standard commissions. Also the users have paid more attention to energy efficiency values of white goods. In this thesis, improving the energy efficiency of the hood was aimed in accordance with these events. On this subject, the level of competition has increased and detailed workings should be necessary improving energy efficiency of hood.
Thesis was worked through 90 centimeter perimetral hood and the hood was A energy efficiency class. Perimetral hood was selected because of considering optimization of perimetral size can increase the energy efficiency value due to decrease the flow rate drop. Perimetral creates air baffle and improves odor reduction factor and collecting oil vapor. So, designed methodology was composed with critical parameter of perimetral size for optimization of perimetral size.
Perimetral structure is especially used by 90cm hoods, because the fan wihich provides air suction, is placed in the top region of the hood structure and this situation directs the water vapor to the start point of top region of the hood. So water vapor can be spread around without suction. Using perimetral directs the air suction to the round of perimetral and air suction is distributed more homogeneously. The air suction of perimetral hood was viewed in the PIV (Particle Image Velocimetry) Room. If the air velocity in the air suction region of the hood, is decreased below critical velocity rate, water vapor spreads around without suction. Therefore, the air velocity should not be decreased below the critical velocity rate which was determined by literature.
First of all, the pressure – airflow rate cure was determined in the wind tunnel and fluid dynamic efficiency and energy efficiency index were calculated according to standards. Fluid dynamic efficiency and energy efficiency index are calculated according to Commission Delegated Regulation (EU) No 65/2014 [4] and Commission Delegated Regulation (EU) No 66/2014 [5]. Aerodynamic Performance Rating is calculated according to IEC 61591 International Standard [3].
According to the first measurement of performance, the perimetral hood had  820 m3/h airflow rate, A class fluid dynamic efficiency and A class energy efficiency index. Then the performance measurement of hood was repeated without perimetral. According to the results, perimetral causes 120 m3/sa airflow rate drop. Therefore, the hood can be reached A+ energy classes when the airflow rate drop of perimetral is removed. 
In this thesis, the effect on airflow rate and air velocity of three parts perimetral structure was analyzed both numerically and experimentally. Perimetral gap with and their places, airflow rate, air velocity of suction area were analyzed in numerical as critical parameters. ANSYS software was used for computational fluid dynamics analysis. 
Before starting to the CFD analysis, the literature search was conducted. According to the research, the turbulence model should be chosen according to very close results to experimental results. The critical air velocity was set at 2,6 m/s according to the minimum flow rate for maximum odor reduction factor from Swedish Energy Agency comments.[6]
Another important issue was to validate the numerical analysis results with experimental datas. Uncertainty analysis of the wind tunnel carried out, that the flow rate measurements of hood is made in. According to uncertainty analysis, the uncertainty rate was 1,54 percent.
The numerical analysis was validated by experimental results which was tested in air tunnel and in 1,54 percent agreement was seen. Then according to numerical results, two equations were created for optimizing perimetral size. They had between 3 and 9 percent agreement.
According to CFD analisys results, increasing X3 parameter ( the width of perimetral gap) that was appeared because of partial perimetral structure, increases the airflow rate of hood. Besides increasing X3 parameter causes decreasing the air velocity of air suction region.
X5 parameter ( the position of the perimetral gap width) has an effect on airflow rate less than X3 parameter' s effect and increasing X5 parameter causes increasing airflow rate. Besides, increasing X5 parameter causes decreasing air velocity of air suction region, but the effect on air velocity of air suction region is very small.
When the perimetral divided 3 parts, air suction is greater around the middle part. Therefore the instantaneous air velocity drop is occurred at the position of the periemtral gap width.
According to CFD analysis results, the effects of X3 and X5 parameters on the airflow rate and air velocity of air suction region were analyzed in Minitab 17 software. Then this effects were formulized with accuracy rates. Because of effects of X3 and X5 parameters on airflow rate and air velocity of air suction region, the relation was created for X3 and X5 parameters as X3*X5. This X3*X5 value was used in the formulas which can be seen below:
air velocity at the corners of the suction (m/s)=61,23-0,06848574.Debi (m^3/s) - %88,3
Airflow rate (m^3/h)=841,97+0,002406.(X3.X5) - %91,4
air velocity at the corners of the suction  (m/s)=3,660-0,000180.(X3.X5) - %97,6
2,6 m/s critical air velocity value was used in the formula and the maximum X3*X5 value was calculated for maximum airflow rate from the formulas. According to calculation, the parameters were determined as X3, X5 vs 15mm, 380mm. The prototype was built for specified model, then the prototype was tested in the wind tunnel. According to test results, the airflow rate was improved 25 m3/h, the fluid dynamic efficiency was improved 1 percent, energy efficiency index was improved 2,1 percent and the annual energy consumption was improved 8 percent. A+ energy class was obtained by these improvements for range hood.