Performance analysis of system heat pump - heat recuperator used for air treatment in process industry

A detailed parametric analysis and performance optimization of the system heat pump - heat recuperator is given in this paper. Mathematical model used for analysis is formed according to the physical model of the system and practical experience. Different types of compressors, and various temperature ranges are treated. Special attention is paid to influence of condensing and evaporating temperatures on system performances, so as to different features of heat recuperator. It is found out that in accordance to the working regimes and the compressor type, it is possible to determine optimal conditions in which the system will consume the minimum of electricity

Performance analysis of system heat pump - heat recuperator used for air treatment in process industry

A detailed parametric analysis and performance optimization of the system heat pump - heat recuperator is given in this paper. Mathematical model used for analysis is formed according to the physical model of the system and practical experience. Different types of compressors, and various temperature ranges are treated. Special attention is paid to influence of condensing and evaporating temperatures on system performances, so as to different features of heat recuperator. It is found out that in accordance to the working regimes and the compressor type, it is possible to determine optimal conditions in which the system will consume the minimum of electricity

Parametri sušenja koštičavog voća

The paper presents the study results on technical and technological parameters in the process of low-temperature drying of stone fruit (plum and apricot) under both laboratory conditions and in a multi-purpose prototype dryer intended for plant material drying. The experimental investigations comprised flow and thermal measurements, technological and kinetic drying parameters. Major emphasis was on temperature and relative humidity of the drying agent and moisture and temperature of the dried material, as well as the drying rate. According to the results obtained, the preheating period was 2-3 hours depending on the type of the material and the drying regime i.e. on the condition of the drying agent. Maximum plum drying rate was recorded 2 h after the beginning of the process and amounted to about 1.15 kg w/kg d.b.h. In the case of apricot drying, maximum drying rate was approx. 0.45 kgw/kg d.b.h. and was registered only 4 hours after the beginning of the drying process, which differed from the plum drying rate under approximately equal drying regime. In addition, the apricot drying kinetics curve differed in shape from the plum drying kinetics curve. The obtained quality of both dried fruits under low-temperature drying conditions was found to meet standard requirements to a great extent primarily respecting sugar and acid loss and the fact that there was no odor or contamination of the fruit. The results obtained showed that, in addition to the technical designs of the drying system, the fruit drying process was found to be significantly affected by how the process itself the duration of which could be reduced, was being managed.U radu su prikazani rezultati istraživanja tehničko tehnoloških parametara procesa niskotemperatuskog sušenja plodova koštičavog voća (šljiva i kajsija). Eksperimentalna istraživanja sprovedena na laboratorijskoj instalaciji i na prototipskoj univerzalnoj sušari namenjenoj za sušenje biljnih materijala, obuhvatila su strujnotermička merenja, parametre kinetike procesa i tehnološke parametre sušenja. Posebno su analizirani temperatura i relativna vlažnost agensa sušenja, vlažnost i temperatura materijala za sušenje kao i brzina sušenja. Rezultati pokazuju da period pregrevanja materijala iznosi od 2-3 h, što je uslovljeno vrstom materijala i režimom sušenja tj. stanjem agensa sušenja. Maksimalna brzina sušenja plodova šljive nastaje nakon 2 h i iznosi oko 1,15 kg w/kg s.m.h. Kod sušenja plodova kajsija maksimalna brzina sušenja iznosi približno 0,45 kgw/kg s.m.h. i pojavljuje se tek nakon 4 časa od početka procesa u čemu se razlikuje od brzine sušenje plodova šljive za približno isti režim sušenja. Pored toga, kriva kinetike sušenja kajsija ima drugačiji oblik u odnosu na krivu sušenja šljiva. Ostvaren kvalitet obe vrste osušenih plodova sa navedenim niskotemperaturskim režimima u velikoj meri odgovara standardima pre svega u pogledu gubitka šećera i kiselina, kao i odsustva bilo kakvih mirisa i zagađenosti plodova. Dobijeni rezultati ukazuju da, pored tehničkih rešenja sistema za sušenje, na uspeh procesa značajan uticaj ima i samo vođenje procesa čije se trajanje može redukovati

Primena uprošćenih termodinamičkih metoda određivanja vremena hlađenja na primeru tehnologije pripreme jogurta dvofaznim hlađenjem

Good cooling and freezing time estimations and predictions can provide efficient and economic performance of refrigeration system for specific technology demands. This paper will review most common methods in engineering practice used for modeling foods with complex shapes in order to calculate cooling and freezing times of foods. Two-phase yogurt manufacturing technology cold room is analyzed from the different aspects of adequate method selections.Dobra procena vremena hlađenja i zamrzavanja može obezbediti efikasniji i ekonomičniji rad rashladne instalacije za postavljene tehnološke zahteve. U ovom radu predstavljene su neke od najčešće primenjivanih metoda za predviđanje vremena hlađenja i zamrzavanja u projektantskoj praksi. Na primeru prve faze tehnologije konzervacije jogurta dvofaznim hlađenjem razmotreno je jedno tehničko rešenje komore za brzo rashlađivanje sa aspekta mogućnosti izbora adekvatne metode termodinamičkog proračuna vremena hlađenja prema odgovarajućoj tehnološki zahtevanoj dinamici hlađenja

Simplified thermodynamic methods for calculation of processing time during food refrigeration applied on two-phase yogurt manufacturing technology

Dobra procena vremena hlađenja i zamrzavanja može obezbediti efikasniji i ekonomičniji rad rashladne instalacije za postavljene tehnološke zahteve. U ovom radu predstavljene su neke od najčešće primenjivanih metoda za predviđanje vremena hlađenja i zamrzavanja u projektantskoj praksi. Na primeru prve faze tehnologije konzervacije jogurta dvofaznim hlađenjem razmotreno je jedno tehničko rešenje komore za brzo rashlađivanje sa aspekta mogućnosti izbora adekvatne metode termodinamičkog proračuna vremena hlađenja prema odgovarajućoj tehnološki zahtevanoj dinamici hlađenja.Good cooling and freezing time estimations and predictions can provide efficient and economic performance of refrigeration system for specific technology demands. This paper will review most common methods in engineering practice used for modeling foods with complex shapes in order to calculate cooling and freezing times of foods. Two-phase yogurt manufacturing technology cold room is analyzed from the different aspects of adequate method selections

Simplified thermodynamic methods for calculation of processing time during food refrigeration applied on two-phase yogurt manufacturing technology

Dobra procena vremena hlađenja i zamrzavanja može obezbediti efikasniji i ekonomičniji rad rashladne instalacije za postavljene tehnološke zahteve. U ovom radu predstavljene su neke od najčešće primenjivanih metoda za predviđanje vremena hlađenja i zamrzavanja u projektantskoj praksi. Na primeru prve faze tehnologije konzervacije jogurta dvofaznim hlađenjem razmotreno je jedno tehničko rešenje komore za brzo rashlađivanje sa aspekta mogućnosti izbora adekvatne metode termodinamičkog proračuna vremena hlađenja prema odgovarajućoj tehnološki zahtevanoj dinamici hlađenja.Good cooling and freezing time estimations and predictions can provide efficient and economic performance of refrigeration system for specific technology demands. This paper will review most common methods in engineering practice used for modeling foods with complex shapes in order to calculate cooling and freezing times of foods. Two-phase yogurt manufacturing technology cold room is analyzed from the different aspects of adequate method selections

Kinetika sušenja koštičavog voća

The results of the investigation of technical and technological parameters in the low temperature drying processes of stone fruit (plum and apricot) under both laboratory conditions and in a universal prototype dryer have been presented in the paper. The measurements comprised flow and thermal measurement, technological and kinetic drying parameters and energy consumption. Major emphasis has been on temperature and relative humidity of the drying agents and humidity and temperature of the drying material. According to results, the preheating period has been found to be approx. 2-3 hours being affected by the type of the material and the drying regime, i.e. by the state of drying agents. Maximal plum drying rate has been after 2 h and amounted to about 1.15 kg w/kg d.b.h. In the case of apricot drying, maximal drying rate has been approx. 0.45 kgw/kg d.b.h. and was registered after 4 hours from the very beginning of the drying process. In addition, the curve of apricot drying kinetics has been differed from the curve of plum drying kinetics. The quality of dry fruit under low temperature drying conditions has been found to meet standard requirements primarily respecting sugar and acid loss and the fact that there was no odour or contamination of fruit. In addition to the technical solutions, the fruit drying process was found to be affected by how the process itself is being managed the duration of which may be shortened contributing to the quality of the products, energy production and profitability.U radu su prikazani rezultati istraživanja tehničko tehnoloških parametara procesa niskotemperatuskog sušenja plodova koštičavog voća (šljiva i kajsija). Eksperimentalna istraživanja sprovedena na laboratorijskoj instalaciji i na prototipskoj univerzalnoj sušari namenjenoj za sušenje biljnih materijala, obuhvatila su strujnotermička merenja, parametre kinetike procesa i tehnološke parametre sušenja. Posebno su analizirani temperatura i relativna vlažnost agensa sušenja, vlažnost i temperatura materijala za sušenje kao i brzina sušenja. Rezultati pokazuju da period predgrevanja materijala iznosi od 2-3 h, što je uslovljeno vrstom materijala i režimom sušenja tj. stanjem agensa sušenja. Maksimalna brzina sušenja plodova šljive nastaje nakon 2 h i iznosi oko 1,15 kg w/kg s. m. h. Kod sušenja plodova kajsija maksimalna brzina sušenja iznosi približno 0,45 kgw/kg s.m.h. i pojavljuje se tek nakon 4 časa od početka procesa u čemu se razlikuje od brzine sušenje plodova šljive za približno isti režim sušenja. Pored toga, kriva kinetike sušenja kajsija ima drugačiji oblik u odnosu na krivu sušenja šljiva. Ostvaren kvalitet obe vrste osušenih plodova sa navedenim niskotemperaturskim režimima u velikoj meri odgovara standardima, pre svega u pogledu gubitka šećera i kiselina, kao i odsustva bilo kakvih mirisa i zagađenosti plodova. Dobijeni rezultati ukazuju da, pored tehničkih rešenja sistema za sušenje, na uspeh procesa značajan uticaj ima i samo vođenje procesa čije se trajanje može redukovati

Kinetika sušenja koštičavog voća

The results of the investigation of technical and technological parameters in the low temperature drying processes of stone fruit (plum and apricot) under both laboratory conditions and in a universal prototype dryer have been presented in the paper. The measurements comprised flow and thermal measurement, technological and kinetic drying parameters and energy consumption. Major emphasis has been on temperature and relative humidity of the drying agents and humidity and temperature of the drying material. According to results, the preheating period has been found to be approx. 2-3 hours being affected by the type of the material and the drying regime, i.e. by the state of drying agents. Maximal plum drying rate has been after 2 h and amounted to about 1.15 kg w/kg d.b.h. In the case of apricot drying maximal drying rate has been approx. 0.45 kgw/kg d.b.h. and was registered after 4 hours from the very beginning of the drying process. In addition the curve of apricot drying kinetics has been differed from the curve of plum drying kinetics. The quality of dry fruit under low temperature drying conditions has been found to meet standard requirements primarily respecting sugar and acid loss and the fact that there was no odor or contamination of fruit. In addition to the technical solutions, the fruit drying process was found to be affected by how the process itself is being managed the duration of which may be shortened contributing to the quality of the products energy production and profitability.U radu su prikazani rezultati istraživanja tehničko tehnoloških parametara procesa niskotemperatuskog sušenja plodova koštičavog voća (šljiva i kajsija). Eksperimentalna istraživanja sprovedena na laboratorijskoj instalaciji i na prototipskoj univerzalnoj sušari namenjenoj za sušenje biljnih materijala, obuhvatila su strujnotermička merenja, parametre kinetike procesa i tehnološke parametre sušenja. Posebno su analizirani temperatura i relativna vlažnost agensa sušenja, vlažnost i temperatura materijala za sušenje kao i brzina sušenja. Rezultati pokazuju da period predgrevanja materijala iznosi od 2-3 h, što je uslovljeno vrstom materijala i režimom sušenja tj. stanjem agensa sušenja. Maksimalna brzina sušenja plodova šljive nastaje nakon 2 h i iznosi oko 1,15 kg w/kg s. m. h. Kod sušenja plodova kajsija maksimalna brzina sušenja iznosi približno 0,45 kgw/kg s.m.h. i pojavljuje se tek nakon 4 časa od početka procesa u čemu se razlikuje od brzine sušenje plodova šljive za približno isti režim sušenja. Pored toga, kriva kinetike sušenja kajsija ima drugačiji oblik u odnosu na krivu sušenja šljiva. Ostvaren kvalitet obe vrste osušenih plodova sa navedenim niskotemperaturskim režimima u velikoj meri odgovara standardima pre svega u pogledu gubitka šećera i kiselina, kao i odsustva bilo kakvih mirisa i zagađenosti plodova. Dobijeni rezultati ukazuju da, pored tehničkih rešenja sistema za sušenje, na uspeh procesa značajan uticaj ima i samo vođenje procesa čije se trajanje može redukovati

Effect of thermal energy storage in energy consumption required for air conditioning system in office building under the african mediterranean climate

In the African Mediterranean countries, cooling demand constitutes a large proportion of total electrical demand for office buildings during peak hours. The thermal energy storage systems can be an alternative method to be utilized to reduce and time shift the electrical load of air conditioning from on-peak to off-peak hours. In this study, the Hourly Analysis Program has been used to estimate the cooling load profile for an office building based in Tripoli weather data conditions. Preliminary study was performed in order to define the most suitable operating strategies of ice thermal storage, including partial (load leveling and demand limiting), full storage and conventional A/C system. Then, the mathematical model of heat transfer for external ice storage would be based on the operating strategy which achieves the lowest energy consumption. Results indicate that the largest rate of energy consumption occurs when the conventional system is applied to the building, while the lowest rate of energy consumption is obtained when the partial storage (demand limiting 60%) is applied. Analysis of results shows that the new layer of ice formed on the surface of the existing ice lead to an increase of thermal resistance of heat transfer, which in return decreased cooling capacity

Effect of thermal energy storage in energy consumption required for air conditioning system in office building under the african mediterranean climate

In the African Mediterranean countries, cooling demand constitutes a large proportion of total electrical demand for office buildings during peak hours. The thermal energy storage systems can be an alternative method to be utilized to reduce and time shift the electrical load of air conditioning from on-peak to off-peak hours. In this study, the Hourly Analysis Program has been used to estimate the cooling load profile for an office building based in Tripoli weather data conditions. Preliminary study was performed in order to define the most suitable operating strategies of ice thermal storage, including partial (load leveling and demand limiting), full storage and conventional A/C system. Then, the mathematical model of heat transfer for external ice storage would be based on the operating strategy which achieves the lowest energy consumption. Results indicate that the largest rate of energy consumption occurs when the conventional system is applied to the building, while the lowest rate of energy consumption is obtained when the partial storage (demand limiting 60%) is applied. Analysis of results shows that the new layer of ice formed on the surface of the existing ice lead to an increase of thermal resistance of heat transfer, which in return decreased cooling capacity