It is reported that cooking can generate many kinds of airborne pollutants,which pose serious threats to human health. Kitchen range-hood is themost effective and popular equipment to exhaust the airborne pollutants,including smoke and oil particle in people’s daily life. The lack of astandardized and overall approach to test and evaluate range-hood makesboth consumer and some manufacturers confused. For these reasons,Lawrence Berkeley National Laboratory published a report, whichshowed the results of their elaborate experiment and some conclusion.However, they also pointed out that due to the limitation of the apparatus,some of the results are not reliable.Therefore, this project established a numerical model in Fluent toinvestigate the pollutant removal performance. Many attempts had beenmade before a validated numerical model was accomplished because aproper model needs the balance between iteration time and resultaccuracy. The validation part is presented in the literature. The captureefficiency curve of the numerical model and one of experiments show agood agreement at the low power input. Some conclusions are drawn onhow power inputs and height affect the capture efficiency, respectively.Dimensionless analysis is done to find a general characteristic curve forevaluating the removal performance of a particular range-hood. / Det rapporteras att matlagning kan generera många typer av luftburnaföroreningar, vilket utgör allvarliga hot mot människors hälsa.Köksfläkten är den mest effektiva och populära utrustningen för attventilera ut luftburna föroreningar, inklusive rök och oljepartiklar imänniskors dagliga liv. Bristen på ett standardiserat och övergripandetillvägagångssätt för att testa och utvärdera köksfläktar ställer bådekonsumenten och vissa tillverkare i okunskap. Av dessa skäl publiceradeLawrence Berkeley National Laboratory en rapport, som visade resultatenav deras utarbetade experiment och en slutsats. Men de påpekade ocksåatt på grund av begränsningen av utrustningen är några av resultaten intehelt tillförlitliga.Därför fastställde detta projekt en numerisk modell i Fluent för attundersöka avlägsnandet av föroreningar. Många försök hade gjorts innanen validerad numerisk modell uppnåddes, eftersom en riktig modellbehöver balansen mellan iterationstid och resultatnoggrannhet.Valideringsdelen presenteras i litteraturen. Effektkurvan för dennumeriska modellen och ett av experimenten visar en godöverensstämmelse vid låg effektinmatning. Några slutsatser dras av hurkraftingångar och höjd påverkar upptagningseffektiviteten.Dimensionslös analys görs för att hitta en generell karaktäristisk kurvaför att utvärdera avlägsnande av prestanda för ett viss köksfläkt.

Studien syftar till att undersöka teorin bakom kortslutningskåpan, dess potential och begränsningar. Undersökningen inleds med en litteraturstudie vilken följs av en fallstudie där ett system med kortslutningskåpa, med avseende på energibehov och systemkostnad, jämförs med ett system med en vanlig kåpa respektive ett system med värmeåtervinning. Litteraturstudien visar att kortslutningskåpan kan minska nettoluftflödet från köket och på så sätt minska uppvärmningsbehovet. Introduceras för stor mängd kortslutningsluft läcker värme och föroreningar från kåpan till köket. Maximalt kunde 21% av det totala frånluftsflödet kortslutas utan läckage. Fallstudiens energiberäkningar har utförts i programmet BELOK Värmeåtervinning samt i ett av författaren kodat program. De tre systemen testades för två fall med olika drifttid, en lunchrestaurang med låg drifttid och en hamburgerrestaurang med hög drifttid. Kortslutningskåpan minskade energibehovet med 15 % och det återvinnande systemet med dryga 80 %. Trots det minskade energibehovet var det värmeåtervinnande systemet inte ekonomiskt lönsamt i lunchrestaurangen, ty drifttiden var för låg för att de höga investeringskostnaderna skulle hinna betala sig. Kortslutningskåpan betalade sig dock efter 4,2 år. I hamburgerrestaurangen, där drifttiden var högre, betalade sig kortslutningskåpan efter 1,3 år och det återvinnande systemet efter 3,2 år. Över 15 år var dock det återvinnande systemet betydligt mer lönsamt. Jämfört med en vanlig kåpa minskade kortslutningskåpan kostnaderna med 13,3 %. Över samma tidsperiod minskade det värmeåtervinnande systemet kostnaderna med 39,5 %. / This study aims to investigate the theory behind the short circuit hood, its potential and limitations. This is done partly as a literature study and partly as a case study where a system with a short circuit hood, in regards of energy demand and system cost, is compared with a system using an exhaust only hood and with a system using heat recovery. The literature study shows that the short circuit hood can reduce the net air flow from the kitchen and thus decrease the heating demand. If too much air is short circuited, heat and contaminations will leak from the hood to the kitchen. A maximum of 21 % of the total exhaust flow could be short circuited without leakage. The energy calculations in the case study were performed using the program BELOK Värmeåtervinning and in a program coded by the author. The three systems were tested for two cases with different operating hours, a lunch restaurant with few operating hours and a hamburger restaurant with many hours. The energy demand was reduced by 15 % using a short circuit hood and by more than 80 % using the heat recovery system. Despite the reduced energy demand, the heat recovery system was not economically profitable in the lunch restaurant, the operating hours were too low for the big investment costs to pay off. However, the short circuit hood payed off after 4,2 years. In the hamburger restaurant where the operating hours was higher, the short circuit hood payed off after 1,3 years and the heat recovery system after 3,2 years. Over 15 years, however, the heat recovery system was significantly more profitable. Compared to an exhaust only system the short circuit hood reduced the costs by 13,3 %. Over the same period, the heat recovery system reduced the costs by 39,5 %.

Regarding the great importance of a good working environment, in this research, ventilation systems installed in kitchens of restaurants were studied in order to avoid problems and to understand the key factors that can influence on the performance of the system. The results obtained were taken into account to provide some recommendations to a real ventilation system of a restaurant called Pastaria in Gävle (Sweden). This concrete ventilation system was not performing good, and some calculations based on the kitchen design were made trying to offset the problem. A large number of scientific studies related to restaurant kitchen hoods and ventilation systems were used to get the findings. These articles were obtained from scholar web databases. The main problem found in kitchen hoods is the inadequate exhaust airflow. The minimum required airflow varies depending on the size and shape of the hood. Keil et al. (2004) found in their research that only 39% and 24% of the studied hoods met the minimum recommended airflow from ACGIH and ASHRAE guidelines, respectively. Other key factors found are related to the kitchen design. The kitchen hood is recommended to have incorporated a capture hood covering all the burners. Side panels can be employed to increase the capture and containment. High efficiency filters and rigid ducts are also recommended. The cleaning of the ventilation ducts is also an important factor, they are recommended to be cleaned between 1 to 9 years depending on the activity of the kitchen. Thus, key factors such as disturbing airflows and the presence/movement of the cooks can disturb the kitchen hood performance. A very effective solution, isolating the fumes below the hood, that is getting developed is the installation of an inclined air curtain from the cooking surface. Related to the kitchen hood and the ventilation system of the Pastaria restaurant. Some measurements and information were obtained in a visit to the restaurant. After calculations, it was obtained based on the kitchen design that is required a minimum airflow of 4 140 m3/hour. In order to do that, the heat exchanger Swegon Silver C RX, installed in the system, requires a minimum size of 11/12. The distribution of the kitchen appliances in this restaurant seems to be correct. However, a future study in order to see if there are disturbing airflows affecting the kitchen hood performance must be carried out. If after checking all recommendations the performance of the kitchen hood is not good enough yet, an inclined air curtain may be installed due to their great effectiveness against problems of hoods. In conclusion, it was clearly obtained that a correct kitchen distribution design and calculations must be done for each restaurant in order to install the most adequate kitchen hood with the best characteristics. This way, fumes, odors, moisture and particles will be easily exhausted allowing a better environment out of risks to the establishment and customers health.