Types, classification and selection of dryers in agroindustry

This paper will provide a review of many publications that have the drying of food material as the primary topic in order to provide a global view of all the problems related to the drying process , selection of adequate dryer for chosen drying materia

Типови, класификација и селекција сушара у агроиндустрији

Sušenje je jedna od osnovnih metoda konzervisanja namirnica u agro-industriji i predstavlja složen i energetski zahtevan proces. Istraživanja u oblasti prirodnih i tehničkih nauka su poslednjih godina fokusirana na procese optimizacije energetski zahtevnih industrijskih sistema u cilju održivog razvoja i osavremenjavanja različitih tehnologija. Veliki broj istraživača se bavi problematikom sušenja u agro-industriji o čemu svedoči i zavidan broj publikacija sa ovom tematikom. Ovim radom učinjen je jedan osvrt na dostupnu literaturu i istraživanja velikog broja autora sa tendencijom da pruži jedan sveobuhvatan uvid na složenost samog procesa sušenja, trendove razvoja opreme i tehnologija, kao i načina pravilnog izbora odgovarajuće tehnologije u zavisnosti od konkretne sirovine koja se suši

Примена савремених технологија сушења у индустрији прераде хране

Proteklih godina je u Republici Srbiji održan veliki broj konferencija, savetovanja i okruglih stolova na temu implementacije energetski efikasnih tehnologija. Usvojeni su zaključci da Republika Srbija, osim Zakona o Energetici, nema propratnih propisa koji bi regulisali projektovanje i izgradnju centara za sušenje, skladištenje i doradu poljoprivrednih proizvoda. Sušenje je jedna od osnovnih tehnoloških operacija u industriji prerade hrane. Skrenuta je pažnja na izuzetno veliki utrošak energije na postrojenjima za sušenje. Neka od predloženih rešenja su racionalizacija potrošnje energije na postojećim postrojenjima i usvajanje novih ekonomičnijih postrojenja baziranih na novim tehnologijama. Ovim radom učinjen je jedan osvrt na dostupnu literaturu i istraživanja velikog broja internacionalnih autora koji se bave naprednim tehnologijama sušenja, unapređenjem energetske efikasnosti sistema sušenja kao i ekološkim aspektima sušenja u cilju obezbeđenja održivog razvoja

Termomehanički procesi pri sušenju prehrambenih materijala u sistemima sa recirkulacijom vazduha

Predmet rada u ovoj disertaciji je istraživanje termomehančkih procesa pri konvektivnom sušenju prehrambenih materijala vlažnim vazduhom kao agensom sušenja u sistemima sa recirkulacijom. Matemtičko-numeričkim metodama i regresionom analizom definisan je fizičko-matematički model koji omogućava simulaciju promene vlažnosti materijala u bezdimenzionom obliku tokom procesa sušenja, a koji uzima u obzir uticaj termomehaničkih osobina vlažnog vazduha (temperature, relativne vlažnosti i brzine strujanja) na proces sušenja. U cilju verifikacije postavljenog modela, osmišljena je i izrađena laboratorijska instalacija za konvektivno sušenje prehrambenih materijala u tankom sloju, koja radi sa potpunom recirkulacijom vazduha. Odabrani materijali (jabuka, krompir i banana) su sušeni pod istim režimima, sa temperaturom sušenja u opsegu 35 , relativnom vlažnoš ÷ 55°C ću u opsegu % 10 ÷ 30 i brzinom strujaja vlažnog vazduha u opsegu 1÷ 2 m s. Jabuke su sušene u komadićima oblika kocke dimenzija 10 mm i 13 mm, krompir u listovima debljina 2 mm i 3 mm, a banana u kolutovima debljina 6 mm i 7 mm. Analiziran je uticaj termomehaničkih osobina vlažnog vazduha na kinetiku procesa sušenja, na osnovu dobijenih vrednosti efektivnog koeficijenta difuzije. Rezultati istraživanja su potvrdili da termomehaničke osobine vlažnog vazduha značajno utiču na proces sušenja, pri čemu se u slučajevima slabijeg uticaja na proces sušenja pojedine veličine mogu zanemariti. Analiziran je rad sistema sušenja koji je podržan radom toplotne pumpe, na osnovu izračunatih vrednosti osnovnih pokazatelja efikasnosti rada sistema. Ustanovljeno je da se pravilno utvrđenim parametrima rada instalacije može uticati na povećanje energetske efikasnosti sistema i smanjenje specifične potrošnje energije po količini izdvojene vlage. Verifikacija dobijenih rezultata izvršena je poređenjem rezultata sopstvenog modela sa rezultatima sprovedenog eksperimentalnog istraživanja, a potom i sa modelima i eksperimentalnim istraživanjima drugih autora.The motivation of the research presented in this thesis was to investigate thermomechanical processes that appears during the convective drying of food materials in systems with air recirculation. The mathematical model was formed to describe the change of moisture ratio of the material during the time, by taking into account the influence of all relevant thermomechanical properties of drying air (temperature, relative humidity and velocity) on the drying process. Convective laboratory scale dryer with possibility of full drying air recirculation was designed and built in order to achieve and measure all relevant drying process parameters. Apples, potatoes and bananas were used in the experiments. The chosen materials were dried under the same drying conditions. Drying air temperature was in range 35-55oC, relative humidity in range 10-30% and velocity in range 1-2 m/s. The apples were cut into cubes with 10 mm and 13 mm side dimension, potatoes were sliced into chips of 2 mm and 3 mm thickness and bananas were sliced into the cylinders with 6 mm and 7 mm thickness. Analysis of error appearance probability was performed. The effective moisture diffusivity was used to describe drying process efficiency. The experimental results confirmed that thermomechanical properties of drying air have significant influence on drying process. It was discovered that drying air, relative humidity could be ignored in some occasions. The performance of heat pump drying system was analyzed in order to discover system efficiency. The system energy and mass flows, air circulation behavior, drying air properties and system components behavior were monitored in order to calculate the main parameters of system performance. It was discovered that appropriate system performance optimization could increase system energy efficiency and reduce specific energy consumption. The results of mathematical model equation were compared with the experimental results and with the models and with the experimental results of the other authors, in order to be verified

Application of modern drying technology in the food processing industry

This paper will provide a review of available publications of many international researchers that deals with advanced drying technologies

Thermomechanical processes in drying of food materials in systems with air recirculation

Predmet rada u ovoj disertaciji je istraživanje termomehanckih procesa pri konvektivnom sušenju prehrambenih materijala vlažnim vazduhom kao agensom sušenja u sistemima sa recirkulacijom. Matemticko-numerickim metodama i regresionom analizom definisan je fizicko-matematicki model koji omogucava simulaciju promene vlažnosti materijala u bezdimenzionom obliku tokom procesa sušenja, a koji uzima u obzir uticaj termomehanickih osobina vlažnog vazduha (temperature, relativne vlažnosti i brzine strujanja) na proces sušenja. U cilju verifikacije postavljenog modela, osmišljena je i izraena laboratorijska instalacija za konvektivno sušenje prehrambenih materijala u tankom sloju, koja radi sa potpunom recirkulacijom vazduha. Odabrani materijali (jabuka, krompir i banana) su sušeni pod istim režimima, sa temperaturom sušenja u opsegu 35 ÷ 55°C , relativnom vlažnošcu u opsegu 10 ÷ 30% i brzinom strujaja vlažnog vazduha u opsegu 1÷ 2 m s . Jabuke su sušene u komadicima oblika kocke dimenzija 10 mm i 13 mm, krompir u listovima debljina 2 mm i 3 mm, a banana u kolutovima debljina 6 mm i 7 mm. Analiziran je uticaj termomehanickih osobina vlažnog vazduha na kinetiku procesa sušenja, na osnovu dobijenih vrednosti efektivnog koeficijenta difuzije. Rezultati istraživanja su potvrdili da termomehanicke osobine vlažnog vazduha znacajno uticu na proces sušenja, pri cemu se u slucajevima slabijeg uticaja na proces sušenja pojedine velicine mogu zanemariti. Analiziran je rad sistema sušenja koji je podržan radom toplotne pumpe, na osnovu izracunatih vrednosti osnovnih pokazatelja efikasnosti rada sistema. Ustanovljeno je da se pravilno utvrenim parametrima rada instalacije može uticati na povecanje energetske efikasnosti sistema i smanjenje specificne potrošnje energije po kolicini izdvojene vlage. Verifikacija dobijenih rezultata izvršena je poreenjem rezultata sopstvenog modela sa rezultatima sprovedenog eksperimentalnog istraživanja, a potom i sa modelima i eksperimentalnim istraživanjima drugih autora...The motivation of the research presented in this thesis was to investigate thermomechanical processes that appears during the convective drying of food materials in systems with air recirculation. The mathematical model was formed to describe the change of moisture ratio of the material during the time, by taking into account the influence of all relevant thermomechanical properties of drying air (temperature, relative humidity and velocity) on the drying process. Convective laboratory scale dryer with possibility of full drying air recirculation was designed and built in order to achieve and measure all relevant drying process parameters. Apples, potatoes and bananas were used in the experiments. The chosen materials were dried under the same drying conditions. Drying air temperature was in range 35-55oC, relative humidity in range 10-30% and velocity in range 1-2 m/s. The apples were cut into cubes with 10 mm and 13 mm side dimension, potatoes were sliced into chips of 2 mm and 3 mm thickness and bananas were sliced into the cylinders with 6 mm and 7 mm thickness. Analysis of error appearance probability was performed. The effective moisture diffusivity was used to describe drying process efficiency. The experimental results confirmed that thermomechanical properties of drying air have significant influence on drying process. It was discovered that drying air, relative humidity could be ignored in some occasions. The performance of heat pump drying system was analyzed in order to discover system efficiency. The system energy and mass flows, air circulation behavior, drying air properties and system components behavior were monitored in order to calculate the main parameters of system performance. It was discovered that appropriate system performance optimization could increase system energy efficiency and reduce specific energy consumption. The results of mathematical model equation were compared with the experimental results and with the models and with the experimental results of the other authors, in order to be verified..

Thermodynamic Analysis of a Cascade Heat Pump Incorporated in High-Temperature Heating System

In this article is presented thermodynamic analysis of a cascade heat pump system designed for using in high-temperature heating systems The own thermodynamic model was built by using properties of working fluids from the Coo/Prop base. The cascade heat pump was designed to use ambient air as heat source with temperature t(amb )= -20 degrees C and for heating water in the high-temperature heating system up to 70 degrees C. The projected heating capacity of the cascade heat pump was 100 kW. The coefficient of performance (COP) of the cascade heat pump system due to use of different working mediums combinations in cycles of the cascade heat pump was investigated. For the best combination of working fluids (mediums) sub-cooling super-heating pressure loss in compressor's suction line, as well as exergy efficiency of the heat pump were analysed as a function of the temperature of the cascade heat exchanger

SOLAR - softver za filtriranje, obradu i vizuelizaciju prikupljenih meteoroloških podataka

The current standards for solar components and systems testing (SRB, EN, ISO, DIN, etc.) imply the determination of the system relevant parameters at the monitored locality. In this regard, it is necessary to prepare all the input data for the selected location in order to determine the standard values, such as: thermal collector performance, factor changes in incident angle of radiation, heat capacity, pressure values and various quality tests. The parameters collected with appropriate measuring instruments are necessary for defining the state of atmospheric moisture air (temperature, relative humidity), air movement (speed and wind direction), ambient characteristic at given location (clouds, precipitation, etc.) and parameters that describe the energetic potential of the Sun (total, direct and diffusion radiation). A software tool for meteorological data processing (SOLAR) is designed and constructed so that the collected data of experimental measurements can be effectively and easily processed, with the possibility to present the results in a number of ways. The basic software components are subroutines for data filtering (extracting the minimum, maximum and average values in the selected time interval of observation), data processing (calculation of unknown characteristic values that are based on experimentally measured values), and visualization of results (graphical representation results).Aktuelni standardi za ispitivanje solarnih komponenata i sistema (SRB, EN, ISO, DIN i drugi) podrazumevaju određivanje svih relevantnih parametara rada instalacije na posmatranom lokalitetu. S tim u vezi, neophodno je pripremiti sve ulazne podatke za odabranu lokaciju radi određivanja standardom definisanih veličina, kao što su: toplotni učinak kolektor, faktor promene upadnog ugla zračenja, toplotnog kapaciteta, padova pritisaka i raznih testova kvaliteta. Veličine koje su od značaja za proračun se mere odgovarajućim mernim instrumentima i neophodne su za definisanje stanja vlažnog atmosferskog vazduha (temperatura, relativna vlažnost), kretanja vazduha (brzina i pravac strujanja vetra), ambijentalnih karakteristika atmosfere na posmatranoj lokaciji (oblačnost, količina padavina, i slično) kao i veličina koje oslikavaju energetski potencijal Sunca na posmatranoj lokaciji (ukupno, direktno i difuzno zračenje). Softver za filtriranje, obradu i vizuelizaciju prikupljenih meteoroloških podataka - SOLAR, osmišljen je i izrađen tako da prikupljene podatke eksperimentalnih merenja efikasno i jednostavno procesuira, a dobijene rezultate potom predstavi korisniku. Osnovne komponente softvera su subrutine za filtriranje podataka (izdvajanje minimalnih, maksimalnih i prosečnih vrednosti u željenom vremenskom intervalu posmatranja), za obradu podataka (izračunavanje nepoznatih karakterističnih veličina koje su od značaja za posmatrani proces na osnovu eksperimentalno merenih veličina) i vizuelizaciju rezultata (grafičko predstavljanje rezultata sa mogućnošću uporednog prikazivanja srodnih veličina i mogućnošću eksportovanja u druge formate pogodne za dalju analizu)

Thermodynamic Analysis of a Cascade Heat Pump Incorporated in High-Temperature Heating System

In this article is presented thermodynamic analysis of a cascade heat pump system designed for using in high-temperature heating systems The own thermodynamic model was built by using properties of working fluids from the Coo/Prop base. The cascade heat pump was designed to use ambient air as heat source with temperature t(amb )= -20 degrees C and for heating water in the high-temperature heating system up to 70 degrees C. The projected heating capacity of the cascade heat pump was 100 kW. The coefficient of performance (COP) of the cascade heat pump system due to use of different working mediums combinations in cycles of the cascade heat pump was investigated. For the best combination of working fluids (mediums) sub-cooling super-heating pressure loss in compressor's suction line, as well as exergy efficiency of the heat pump were analysed as a function of the temperature of the cascade heat exchanger

Analiza efikasnosti rada sistema toplotne pumpe za hlađenje svežeg mleka sa predhlađenjem i mogućnošću iskorišćenja otpadne toplote za dogrevanje potrošne vode

Contemporary livestock production implies production of highly valuable, biologically and chemically safe products. Dairy production has no exception too. On the contrary, the quality standards for raw milk are highly increased. The quality of raw milk is defined by its chemical composition and the total count of microorganisms in control volume. In this paper we discussed the performance of advanced system for heat recovery from raw milk and its application in the process of preheating and preparation of process water. The energy and exergy efficiency of one of such systems were analyzed. It was determined that the implementation of the system for milk cooling with precooling and using the waste heat for preheating process water could achieve significant savings. The system consists of 'milk to water' heat pump, pre-cooler for milk cooling and storage tank for process water with heating possibility. Values of exergy efficiency of each component of system and potential improving of components performances were determined. Also, the exergy efficiency and potential improvement of complete system were determined.Savremena stočarska proizvodnja podrazumeva proizvodnju visoko vrednih, biološki i hemijski bezbednih proizvoda. Proizvodnja mleka nije izuzetak, naprotiv, norme kvaliteta sirovog mleka su sve strožije. Kvalitet sirovog mleka je određen njegovim hemijskim sastavom i ukupnom brojnošću mikroorganizama u kontrolnoj zapremini. U ovom radu biće razmatran rad naprednog sistema za rekuperaciju toplote iz svežeg mleka koja se potom koristi u procesu dogrevanja i pripreme potrošne vode. Primenom sistema za hlađenje mleka sa predhlađenjem i korišćenjem dobijene toplote za zagrevanje potrošne vode mogu se postići značajne uštede. U radu je analizirana energetska i eksergetska efikasnost rada jednog ovakvog sistema. Sistem se sastoji od toplotne pumpe 'mleko-voda', predhladnjaka za hlađenje svežeg mleka i skladišnika potrošne tople vode sa mogućnošću njenog dogrevanja. Ustanovljene su veličine eksergetske efikasnosti komponenata sistema i potencijal poboljšanja svake od komponenata u sistemu. Takođe, ustanovljena je eksergetska efikasnost celokupnog sistema i potencijal njegovogpoboljšanja