Analiza mogućnosti smanjenja emisija čađe i NOx na suvremenim sporohodnim dizelskim dvotaktnim motorima

The reduction of NOx and soot emissions are, besides improvement of fuel efficiency, the main goals of the development of modern diesel engines. The manufacturers of large marine engines are developing systems that allow great operation flexibility and different strategies that allow the mentioned goals. Except for experimental measurements, the computer simulation is a tool that is used for this scope. 3D numerical simulations are the most appropriate for the calculation of pollutant production. The large marine engines are specific for their size, fuel used, location of the injectors and small revolution rate. In the present work, a large marine engine model was developed with the OpenFOAM software toolbox. A heavy fuel oil and a soot model were built in. Spray model parameters were tuned. A set of different calculation meshes was tested. The model validation was performed on a constant volume combustion chamber, an automotive engine and, finally, on a large marine engine. After a satisfactory matching with experimental measurements, a set of numerical simulations was performed by which the possibility of emission reduction was evaluated. The strategies of scavenging air temperature reduction, exhaust gas recirculation and alternative injection patterns were used. After the end of the analysis all the methods resulted in a reduction of pollutant emissions. * Defended Doctoral Thesis (2010)Smanjenje emisija dušikovih oksida i čađe uz povećanje stupnja djelovanja glavni su ciljevi kod razvoja suvremenih dizelskih motora. Proizvođači velikih brodskih motora razvijaju sustave koji omogućuju veliku fleksibilnost u radu i različite strategije koje omogućuju postizanje spomenutih ciljeva. U tu svrhu se osim mjerenja koriste kompjutorske simulacije. Za proračun tvorbe štetnih tvari najprikladnije su 3D numeričke simulacije. Veliki brodski motor specifičan je zbog svojih dimenzija, zbog goriva koje koristi, zbog smještaja rasprskača te zbog male brzine vrtnje. U radu je razvijen model velikog brodskog motora pomoću OpenFOAM programskog kompleta alata. Ugrađen je model teškog goriva i model za čađu. Korigirani su parametri modela mlaza. Testiran je čitav raspon proračunskih mreža različitih karakteristika. Validacija je vršena na komori izgaranja konstantnog volumena, na vozilskom motoru i konačno na velikom brodskom motoru. Nakon što je postignuto zadovoljavajuće poklapanje s eksperimentalnim mjerenjima, izvršena je serija numeričkih simulacija pri čemu su analizirane mogućnosti smanjenja emisija. Korištene su strategije smanjenja temperature ispirnog zraka, recirkulacije ispušnih plinova te alternativnih strategija ubrizgavanja goriva. Sve analizirane metode rezultirale su smanjenjem emisije štetnih tvari. * Obranjena doktorska disertacija (2010.

PIGS BREEDING FOR THE PRODUCTION OF TRADITIONAL MEAT PRODUCTS

Plodna Slavonija poznata je po proizvodnji više vrsta suhomesnatih proizvoda: kulenu, kulenovoj seki, kobasici, šunki i slanini, ali i drugim svinjskim prerađevinama (krvavici, švarglu, čvarcima, masti). Za njihovu proizvodnju potrebne su „zrele svinje“ odgovarajuće klaoničke kvalitete. Proizvodnja svinja za tradicionalne mesne proizvode može se odvijati u različitim proizvodnim sustavima (otvorenima, zatvorenima, poluotvorenima, „organskima“). Svaki od navedenih sustava daje specifičnu kvalitetu svinja za klanje, a time i njihovih proizvoda. Proizvodni sustavi mogu značajno utjecati na performanse rasta te kvalitetu trupa i mesa svinja. Taj utjecaj proizlazi iz međusobnoga djelovanja uvjeta držanja, količine i sastava hrane i korištenoga genotipa svinja. Odabir sustava proizvodnje ovisan je o lokalnim proizvodnim uvjetima, genotipu svinja, zahtjevima potrošača (tržišta) za određenom kvalitetom proizvoda i drugim čimbenicima. Slavonski tradicionalni mesni proizvodi mogu svojom kvalitetom biti prepoznatljivi hrvatski brend na domaćem i inozemnome tržištu. Za proizvodnju tih proizvoda standardne kvalitete, potrebne su i svinje standardne kvalitete, o čijoj se proizvodnji u ovoj knjizi i raspravlja.The fertile Slavonia is known for production of several types of cured meats: kulen, kulen sis, sausage, ham and bacon, and other pork products (“krvavica” - blood sausage, “švargl” - a type of brawn where chopped parts of head are stuffed inside the pig’s stomach, “čvarci” - a variant of pork crisps, fat). These products require “mature pigs” of adequate slaughter quality. Production of pigs intended for traditional meat products may take place in different production systems (open, closed, semi-open, “organic”). Each of these systems provides a specific quality of pigs for slaughter, reflecting on the quality of the final product. Production systems can have a significant impact on growth performance and carcass and meat quality of pigs. This effect arises from the interaction between housing conditions, the amount and composition of food and used pig genotype. The choice of a production system depends on local production conditions, pig genotype, consumer demand (market) for a given product quality, and other factors. Due to their quality, the traditional Slavonian meat products can become a recognizable Croatian brand in both domestic and international markets. Production of standard quality products requires standard quality of pigs. Therefore this book is focused on such pigs production

GENETSKI MARKERI KRVI U SELEKCIJI PROTIV STRES-SINDROMA U SVINJA I LOŠA KVALITETA MESA

Osim korisnih učinaka (veća mesnatost i bolja konformacija polovica), Halⁿ gen i negativno djeluje (slabija plodnost, sklonost stresu i iznenadnim uginućima, slabija kvaliteta mesa) uzrokujući štetu koja nadmašuje korisne učinke. Zavisno o selekciiskom cilju, selekcijska strategija može biti potpuno iskorjenjivanje Halⁿ gena iz populacije ili iskorištavanie prednosti heterozigotnog potomstva (Halᴺⁿ) nastalog križanjem homozigotnih očeva (Halⁿⁿ) s homozigotnim majkama (Halᴺᴺ). S obzirom da se halotan-testom ne mogu otkriti heterozigotne životinje (Halᴺⁿ), selekcijski ciljevi mogu se ostvariti samo kombiniranom primjenom haloten-testa i određvanjem tipa krvi tj. genetskih markera. Genski lokus koji kontrolira reakciju svinja Halotan (Halⁿⁿ) nalazi se na istom cromosomu s genskim lokusom za sustav enzima fosfo-heksoizomeraze (PHI), s lokusima za sustave krvnih grupa S i H, s lokusom za postalbumin-2 (PO2) te s lokusom za sustav enzima 6-fosof-glukodehidrogenaze (6-pGD). Elektroforezom i imunokemijskim metodama mogu se u krvi utvrditi proizvodi gena tijesno povezanih s Hal genom, pri čemu ovi geni mogu poslužiti kao njegovi genetski markeri. Izbor gena-markera (alela) pri selekciji protiv Halⁿ gena, odnosno stres-sindroma i slabe kvalitete mesa, zavisan je o određenoj populaciji svinja

Analisys of soot and nox emissions reduction possibilities on modern low speed, two stroke, diesel engines

Smanjenje emisija dušikovih oksida i čađe uz povećanje stupnja djelovanja glavni su ciljevi kod razvoja suvremenih dizelskih motora. Proizvođači velikih brodskih motora razvijaju sustave koji omogućuju veliku fleksibilnost u radu i različite strategije koje omogućuju postizanje spomenutih ciljeva. U tu svrhu se osim mjerenja koriste kompjutorske simulacije. Za proračun tvorbe štetnih tvari najprikladnije su 3D numeričke simulacije. Veliki brodski motor specifičan je zbog svojih dimenzija, zbog goriva koje koristi, zbog smještaja rasprskača te zbog male brzine vrtnje. U radu je razvijen model velikog brodskog motora pomoću OpenFOAM programskog kompleta alata. Ugrađen je model teškog goriva i model za čađu. Korigirani su parametri modela mlaza. Testiran je čitav raspon proračunskih mreža različitih karakteristika. Validacija je vršena na komori izgaranja konstantnog volumena, na vozilskom dizelskom motoru i konačno na velikom brodskom motoru. Nakon što je postignuto zadovoljavajuće poklapanje s eksperimentalnim mjerenjima, izvršena je serija simulacija pri čemu su analizirane mogućnosti smanjenja emisija. Korištene su strategije smanjenja temperature ispirnog zraka, recirkulacije ispušnih plinova te alternativnih obrazaca ubrizgavanja. Nakon izvršene analize, sve testirane metode su se pokazale kao djelotvorne u smanjenju emisija štetnih tvari.The reduction of NOx and soot emissions are, beside the improvement of fuel efficiency, the main goals of the development of modern diesel engines. The manufacturers of large marine engines are developing systems that allow a great operation flexibility and different strategies that allow the mentioned goals. Except experimental measurements, the computer simulation is a tool that is used for this scope. 3D numerical simulations are the most appropriate for the calculation of the pollutants production. The large marine engines are specific for their size, for the fuel used, for the location of the injectors and for the small revolution rate. In the present work a large marine engine model was developed with the OpenFOAM software toolbox. A heavy fuel oil and a soot model were built in. Spray model parameters were tuned. A set of different calculation meshes was tested. The model validation was performed on a constant volume combustion chamber, on an automotive diesel engine and finally on a large marine engine. After a satisfactory matching with experimental measurements, a set of simulations was performed by which the possibility of emissions reduction was evaluated. The strategies of scavenging air temperature reduction, exhaust gas recirculation and alternative injection patterns were used. After the end of the analysis all the methods resulted in a reduction of pollutant emissions

OTKRIVANJE SVINJA SKLONIH MALIGNOJ HIPERTERMIJI (STRES-SINDROMU)

Sklonost svinja malignoj hipertermiji (stres sindromu) posljedica je intenzivne i jednostrane selekcije na visoku mesnatost. Najmanja je učestalost stresu sklonih svinja u populacijama velikog jorkšira, a najveće kod izrazito mesnatih pasmina svinja (pietren, belgijski landras). Svinje sklone stres sindromu obilježavaju slabija vitalnost, češća iznenadna uginuća, osobito tijekom transporta, slabija plodnost, te izražena mesnatost uz učestaliju pojavu mesa lošije kakvoće (blijedo, mekano, vodnjikavo, tzv. BMV meso). Za otkrivanje stresu sklonih svinja postoji više postupaka (metoda), a najčešće se primjenjuju: halotan test, CK test i metoda lančane reakcije polimerazom. Zbog bržeg provođenja i pouzdanosti, metoda lančane reakcije polimerazom je najprihvatljivija

FATTENING AND SLAUGHTERING TRAITS OF BLACK SLAVONIAN PIGS FED DIETS WITH AND WITHOUT GREEN FEED (ALFALFA)

Važnost dodavanja voluminoznih krmiva, osobito zelene mase, zbog nižeg sadržaja energije, je višestruka za svinje masnijih genotipova poput crne slavonske svinje. Crne slavonske svinje, hranjene s obrokom od krmne smjese i zelene mase (lucerne) u odnosu na svinje hranjene samo s krmnom smjesom, u tovu od 30 do 130 kg tjelesne mase, imaju nešto manje dnevne priraste (520 g : 645 g), manju dnevnu konzumaciju krmne smjese (2,47 kg : 2,90 kg), veći utrošak krmne smjese za kg prirasta (4,75 kg : 4,50 kg) i veću mesnatost svinjskih polovica (45,92% : 39,24%). Crne slavonske svinje hranjene obrokom bez zelene mase imaju, pak, višu pH1 i pH2 vrijednost mesa (6,53 : 6,00 i 5,86 : 5,60), te veći stupanj svjetloće L* (50,78 : 47,87), manje vode (67,70% : 71,52%) i sirovih proteina (20,40% : 21,58%), a više sirove masti (10,36% : 6,88%) u odnosu na meso svinja hranjenih obrokom s krmnom smjesom i zelenom masom. Crne slavonske svinje, zbog sklonosti taloženja masnog tkiva u trupu, preporučuje se u poluotvorenom sustavu hraniti obrocima sa zelenom masom (lucernom).Addition of forage, especially green plant material, to the fodder of pigs of more fatty genotypes, such as Black Slavonian pigs, is of multiple importance due to its lower energy content. Compared to the pigs fed with forage mixture only, Black Slavonian pigs fed with rations consisting of both forage mixture and green plant material (Alfalfa), fattened from 30 to 130 kg bodyweight, have a little lower daily weight gain (520 g : 645 g), lower daily feed consumption (2.47 kg : 2.90 kg), a higher consumption of forage mixture per kg gain (4.75 kg : 4.50 kg) and leaner pig carcasses (45.92% : 39.24%). In turn, Black Slavonian pigs fed rations without green plant material have higher pH1 and pH2 values of meat (6.53 : 6.00 and 5.86 : 5.60), and a higher level of brightness L * (50.78 : 47.87 ), lower water content (67.70% : 71.52%) and protein level (20.40% : 21.58%), and a higher level of crude fat (10.36% : 6.88%), compared to the pigs fed rations consisting of both forage mixture and green plant material. Given the tendency to deposit fat in the trunk, Black Slavonian pigs kept in the semi-open system should be fed rations containing green plant metarial (Alfalfa)

Thermodynamic Analysis of Steam Cooling Process in Marine Power Plant by Using Desuperheater

Thermodynamic (energy and exergy) analysis of steam cooling process in the marine steam propulsion plant is presented in this research. Steam cooling is performed by using Desuperheater which inject water in the superheated steam to obtain wet steam. Wet steam is used in auxiliary heaters for various heating purposes inside the marine steam propulsion system. Auxiliary heaters require wet steam due to safety reasons and for easier steam condensation after heat transfer. Analysis of steam cooling process is performed for a variety of steam system loads. Mass flow rates of cooling water and superheated steam in a properly balanced cooling process should have the same trends at different system loads - deviations from this conclusion is expected only for a notable change in any fluid temperature. Reduction in steam temperature is dependable on the superheated steam temperature (at Desuperheater inlet) because the temperature of wet steam (at Desuperheater outlet) is intended to be almost constant at all steam system loads. Energy losses of steam cooling process for all observed system loads are low and in range between 10–30 kW, while exergy losses are lower in comparison to energy losses (between 5–15 kW) for all loads except three the highest ones. At the highest system loads exergy losses strongly increase and are higher than 20 kW (up to 40 kW). The energy efficiency of a steam cooling process is very high (around 99% or higher), while exergy efficiency is slightly lower than energy efficiency (around 98% or higher) for all loads except the highest ones. At the highest steam system loads, due to a notable increase in cooling water mass flow rate and high temperature reduction, steam cooling process exergy efficiency significantly decreases, but still remains acceptably high (between 95% and 97%). Observation of both energy and exergy losses and efficiencies leads to conclusion that exergy analysis consider notable increase in mass flow rate of cooling water which thermodynamic properties (especially specific exergies) strongly differs in comparison to steam. Such element cannot be seen in the energy analysis of the same system

La calidad nutritiva de los huevos en la nutrición humana

Za ljudski organizam jaja sadrže sve potrebne hranjive tvari, ali u nedovoljnim količinama. Konzumna jaja su prirodno pakirana namirnica (konzerva), bogata rezervnim hranjivim tvarima, vrlo važna u ljudskoj prehrani. Sadrže sve za život potrebne hranjive tvari, a naročito su dobar izvor esencijalnih aminokiselina, esencijalnih masnih kiselina, vitamina topivih u mastima, vitamina B12 i kolina, lecitina, željeza, fosfora i drugog. Iako sadrže kolesterol, prema novijim istraživanjima za većinu ljudske populacije on nije uzrok hiperkolesterolemije i kardiovaskularnih bolesti. Zbog visoke nutritivne gustoće (odnosa energije i hranjivih tvari) naročito su pogodna za prehranu osjetljivih populacijskih skupina ljudi (djece, staraca, kroničnih bolesnika, trudnica).Eggs contain all the nutrients required by the human body. Such nutrients are, however, present in the amounts that are by themselves considered insufficient. Shell eggs are naturally packaged (canned) foods rich in reserve nutrients that make an important contribution to the human diet. They contain all essential nutrients and are a particularly good source of essential amino acids, essential fatty acids, fat-soluble vitamins, vitamin B12 and choline, lecithin, iron, phosphorus and others. While it is true that eggs do contain cholesterol, recent studies have found that cholesterol is not the cause of hypercholesterolemia and cardiovascular disease for the majority of human population. Due to their high nutrient density (relationship between energy and nutrients), eggs are particularly suitable for the diet of sensitive population groups (children, the elderly, the chronically ill, pregnant women).Eier enthalten alle für den menschlichen Körper notwendigen Nährstoffe, jedoch nicht in ausreichenden Mengen. Das Hühnerei ist ein Lebensmittel in einer natürlichen Verpackung (Konserve), reich an Reservenährstoffen, das für die menschliche Ernährung eine bedeutende Rolle spielt. Eier enthalten lebenswichtige Nährstoffe und sind eine besonders gute Quelle von essentiellen Aminosäuren, essentiellen Fettsäuren, fettlöslichen Vitaminen, Vitamin B12, Cholin, Lezithin, Eisen, Phosphor u.a. Obwohl sie Cholesterin enthalten, zeigen jüngste Forschungen, dass Eier für die Mehrheit der Menschen nicht die Ursache von erhöhtem Cholesterinspiegel und Herz- und Gefäßkrankheiten sind. Aufgrund der hohen Nährdichte (Verhältnis zwischen der Energie und den Nährstoffen) eignen sie sich insbesondere für die Ernährung vom empfindlichen Menschengruppen (Kinder, ältere Menschen, chronische Patienten, Schwangere).Le uova contengono quasi tutte le sostanze nutrienti necessarie per l’organismo umano, ma in quantità insufficienti. Le uova destinate all’alimentazione umana sono un cibo dotato di “imballaggio” naturale e sono ricche di sostanze nutritive molto importanti per l’alimentazione umana. Esse sono una miniera di sostanze nutritive necessarie alla vita dell’uomo; in particolare, sono una buona fonte di amminoacidi essenziali, acidi grassi essenziali, vitamine liposolubili, vitamine B12 e poi colina, lecitina, ferro, fosforo ecc. Benché contengano colesterolo, secondo recenti studi le uova non rappresentano una delle cause dell’ipercolesterolemia e delle malattie cardiovascolari per la gran parte della popolazione mondiale. Grazie alla loro alta densità nutritiva (data dal rapporto tra energia e sostanze nutrienti), sono particolarmente adatte all’alimentazione dei gruppi sensibili della popolazione umana (bambini, vecchi, malati cronici, donne in stato di gravidanza).Los huevos contienen todos los nutrientes necesarios para el organismo humano, pero no en las cantidades suficientes. Los huevos de consumo son un alimento en un embalaje natural (conserva), rico en nutrientes y muy importante para la nutrición humana. Contienen todos los nutrientes importantes para la vida y son un buen fuente de los aminoácidos esenciales, ácidos grasos esenciales, vitaminas liposolubles, del vitamina B12 y de la colina, de lecitina, hierro, fósforo y otros elementos. Aunque contienen también el colesterol, según nuevas investigacione este colesterol no causa la hipercolesterolemia ni las enfemedades cardiovasculares en la mayoría de la población humana. Son apropiados para la dieta de los grupos de población sensibles (niños, personas viejas, pacientes crónicos, mujeres embarazadas) por su densidad nutricional (la relación entre la energía y los nutrientes)