This paper presents a study carried out to investigate the performance of a hybrid photovoltaic/thermal crop dryer in hot humid region of Umuagwo-Ohaji in the South-east region of Nigeria, through energy and exergy analyses, drying, electrical and thermal efficiencies, energy utilization and energy utilization ratio, sustainability indicators such as waste energy ratio (WER), sustainability index (SI) and improvement potential (IP). Drying experiments were conducted at varying inlet air temperatures (50, 60 and 70 o C), airflow rates (1.14, 2.29 and 3.43 kgs -1 ) and slice thicknesses (10, 15 and 20 mm) on 500g batch size of red pepper slices during sunshine periods. Results obtained show that the total and specific energy consumption for drying a batch of sliced red pepper samples varied between 2.08 – 34.91kJ and 7.04 – 62.76 kJkg -1 , respectively. The energy utilization and energy utilization ratio during the drying process ranged from 195.75 – 3013.21 Js -1 and 1.82 – 20.4%, respectively. The energy and exergy efficiencies varied between 15.6738.17% and 26% to 88%, respectively. The mean drying efficiency of the system ranged from 7.12 – 40.27%. The maximum electrical and thermal efficiencies of 23.86% and 93.03%, respectively were obtained. A waste energy ratio of 0.0827 0.1579 was obtained, whereas SI and IP values ranged between 1.137 ≤ SI ≤ 6.119 and 0.198 ≤ IP ≤0.583kW, respectively. There is certainly a wide range of improvement in the PV/T system as 12.1 – 18.4 % of the solar irradiance was consumed for drying. Prospects for improvement and recommendations for further studies were suggested.
{"title":"Performance of hybrid photovoltaic/thermal crop dryer in hot humid Nigerian region","authors":"Sampson Uzoma, N. Nwakuba, Kelechi E. Anyaoha","doi":"10.5937/POLJTEH1902056U","DOIUrl":"https://doi.org/10.5937/POLJTEH1902056U","url":null,"abstract":"This paper presents a study carried out to investigate the performance of a hybrid photovoltaic/thermal crop dryer in hot humid region of Umuagwo-Ohaji in the South-east region of Nigeria, through energy and exergy analyses, drying, electrical and thermal efficiencies, energy utilization and energy utilization ratio, sustainability indicators such as waste energy ratio (WER), sustainability index (SI) and improvement potential (IP). Drying experiments were conducted at varying inlet air temperatures (50, 60 and 70 o C), airflow rates (1.14, 2.29 and 3.43 kgs -1 ) and slice thicknesses (10, 15 and 20 mm) on 500g batch size of red pepper slices during sunshine periods. Results obtained show that the total and specific energy consumption for drying a batch of sliced red pepper samples varied between 2.08 – 34.91kJ and 7.04 – 62.76 kJkg -1 , respectively. The energy utilization and energy utilization ratio during the drying process ranged from 195.75 – 3013.21 Js -1 and 1.82 – 20.4%, respectively. The energy and exergy efficiencies varied between 15.6738.17% and 26% to 88%, respectively. The mean drying efficiency of the system ranged from 7.12 – 40.27%. The maximum electrical and thermal efficiencies of 23.86% and 93.03%, respectively were obtained. A waste energy ratio of 0.0827 0.1579 was obtained, whereas SI and IP values ranged between 1.137 ≤ SI ≤ 6.119 and 0.198 ≤ IP ≤0.583kW, respectively. There is certainly a wide range of improvement in the PV/T system as 12.1 – 18.4 % of the solar irradiance was consumed for drying. Prospects for improvement and recommendations for further studies were suggested.","PeriodicalId":281326,"journal":{"name":"Poljoprivredna tehnika","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117345197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Miodragović, I. Mileusnić, M. Balać, Marija Milovanović
{"title":"Research of Claas Lexion 430 harvester exploitation in soya harvest","authors":"M. Miodragović, I. Mileusnić, M. Balać, Marija Milovanović","doi":"10.5937/POLJTEH1902076M","DOIUrl":"https://doi.org/10.5937/POLJTEH1902076M","url":null,"abstract":"","PeriodicalId":281326,"journal":{"name":"Poljoprivredna tehnika","volume":"121 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129212954","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Pajić, S. Oparnica, M. Oljaca, K. Gligorević, M. Drazic, I. Zlatanović, Biljana Bošković
{"title":"Mapping treatments of chemical protection in barley production by using the precision agriculture technology","authors":"M. Pajić, S. Oparnica, M. Oljaca, K. Gligorević, M. Drazic, I. Zlatanović, Biljana Bošković","doi":"10.5937/POLJTEH1902047P","DOIUrl":"https://doi.org/10.5937/POLJTEH1902047P","url":null,"abstract":"","PeriodicalId":281326,"journal":{"name":"Poljoprivredna tehnika","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115625580","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Hydraulic symbols - Part Two: Pumps and actuators","authors":"V. Petrović, B Vera Cerović","doi":"10.5937/POLJTEH1902001P","DOIUrl":"https://doi.org/10.5937/POLJTEH1902001P","url":null,"abstract":"","PeriodicalId":281326,"journal":{"name":"Poljoprivredna tehnika","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126065013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A field performance analysis of a developed prototype tractor-drawn turmeric planter is presented. The experiment was randomized in a factorial design of three planter levels of rhizome lengths (30, 45 and 60 mm) and operational speeds of 8, 10, and 12 kmh -1 . An average mass of 3 kg of wholesome turmeric rhizomes were introduced into the hopper of the planter and planted in 90 m 2 of experimental plot. During field evaluation of the machine, the effective field capacity, field efficiency, missing index, multiple index and planting depth were considered; whereas laboratory tests were conducted to evaluate the planter’s seed rate, percentage rhizome bruise wheel slippage and fuel consumption. Results obtained show that the maximum seed rate was 0.283 th -1 . The maximum percent bruised turmeric rhizome was found to be 30.08%. The mean effective field capacity varied between 0.63 0.96 hah -1 , at operational speeds of 8 and 12 kmh -1 , respectively and 45 mm rhizome length. The mean field efficiency was obtained to be 65.8%. The maximum wheel slippage of 4.37% and fuel consumption of 3.8 lha -1 were obtained at the machine speeds of 8 kmh -1 and 12 kmh -1 , respectively; whereas the minimum wheel slippage of 3.14% and fuel consumption of 2.2 lha -1 were obtained at the machine speeds of 12 kmh -1 and 8 kmh -1 , respectively for the range of the studied turmeric rhizome length. The highest and lowest percentage turmeric rhizome miss index of 35% were recorded for turmeric rhizome length of 30 mm at a speed of 10 kmh -1 and 8 kmh -1 , respectively. An average planting depth of 68 mm was obtained. The numerical optimization approach was adopted to obtain an optimal operational parameters of 12 kmh -1 speed and 45 mm turmeric rhizome grading size with an overall desirability index of 0.73. An economic evaluation was calculated using the principle of payback period which was obtained to be very small (1.64 years) compared to the life of the planter of 17 years. Prospects for future works were suggested.
介绍了一种新型拖拉机牵引型姜黄种植样机的田间性能分析。试验采用随机因子设计，根茎长度为30、45和60 mm，种植速度为8、10和12 km / h -1。将平均质量为3公斤的健康姜黄根茎引入播种机的料斗中，种植在90平方米的试验田中。在田间评价时，考虑了有效田容量、田效率、缺失指数、多重指数和种植深度;而实验室试验则对播种机的播种率、根茎擦伤率、轮滑率和燃料消耗进行了评估。结果表明，种子率最高可达0.283 th -1。姜黄根茎的最大伤损率为30.08%。在运行速度为8和12 km / h -1和根茎长度为45 mm时，平均有效田间容量变化在0.63 ~ 0.96 hah -1之间。平均田间效率为65.8%。车速为8 km / h -1和12 km / h -1时，最大轮滑为4.37%，油耗为3.8 lha -1;在研究的姜黄根茎长度范围内，当转速为12 km / h -1和8 km / h -1时，轮滑最小为3.14%，油耗为2.2 lha -1。在10 km / h -1和8 km / h -1速度下，姜黄根茎长度为30 mm时，脱靶率最高为35%，脱靶率最低。平均种植深度为68毫米。采用数值优化方法，得到最佳操作参数为12 km / h -1速度和45 mm姜黄分级粒度，总体理想指数为0.73。利用投资回收期原则进行经济评价，与种植机17年的寿命相比，获得的投资回收期非常短(1.64年)。并对今后的工作提出了展望。
{"title":"Field performance analysis of a tractor-drawn turmeric rhizome planter","authors":"C. Muogbo, A. Gbabo, N. Nwakuba","doi":"10.5937/POLJTEH1902033M","DOIUrl":"https://doi.org/10.5937/POLJTEH1902033M","url":null,"abstract":"A field performance analysis of a developed prototype tractor-drawn turmeric planter is presented. The experiment was randomized in a factorial design of three planter levels of rhizome lengths (30, 45 and 60 mm) and operational speeds of 8, 10, and 12 kmh -1 . An average mass of 3 kg of wholesome turmeric rhizomes were introduced into the hopper of the planter and planted in 90 m 2 of experimental plot. During field evaluation of the machine, the effective field capacity, field efficiency, missing index, multiple index and planting depth were considered; whereas laboratory tests were conducted to evaluate the planter’s seed rate, percentage rhizome bruise wheel slippage and fuel consumption. Results obtained show that the maximum seed rate was 0.283 th -1 . The maximum percent bruised turmeric rhizome was found to be 30.08%. The mean effective field capacity varied between 0.63 0.96 hah -1 , at operational speeds of 8 and 12 kmh -1 , respectively and 45 mm rhizome length. The mean field efficiency was obtained to be 65.8%. The maximum wheel slippage of 4.37% and fuel consumption of 3.8 lha -1 were obtained at the machine speeds of 8 kmh -1 and 12 kmh -1 , respectively; whereas the minimum wheel slippage of 3.14% and fuel consumption of 2.2 lha -1 were obtained at the machine speeds of 12 kmh -1 and 8 kmh -1 , respectively for the range of the studied turmeric rhizome length. The highest and lowest percentage turmeric rhizome miss index of 35% were recorded for turmeric rhizome length of 30 mm at a speed of 10 kmh -1 and 8 kmh -1 , respectively. An average planting depth of 68 mm was obtained. The numerical optimization approach was adopted to obtain an optimal operational parameters of 12 kmh -1 speed and 45 mm turmeric rhizome grading size with an overall desirability index of 0.73. An economic evaluation was calculated using the principle of payback period which was obtained to be very small (1.64 years) compared to the life of the planter of 17 years. Prospects for future works were suggested.","PeriodicalId":281326,"journal":{"name":"Poljoprivredna tehnika","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129372108","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hydraulic power transfer and management systems are widely used in modern agriculture, especially in agricultural engineering and the associated processing industry. They can be very simple, but also extremely complex, when precise matching of the interaction of their components in real time is very difficult to controll and achieve. In addition, the designs of a number of hydraulic components is sufficiently complicated for detailed representation on the corresponding hydraulic installation. In all cases, analyzing the performance characteristics of components and the entire hydraulic system, as well as understanding the structure of the hydraulic system, is of great importance. One of the generally accepted ways to facilitate and speed up these processes is the application of schematic diagrams of hydraulic systems and their subcircuits. Officially, hydraulic symbols are defined by ISO industry standards. Therefore, ideally, all hydraulic schemes should be configured using universal graphic symbols. Unfortunately, this is not always the case in technical practice. Depending on the manufacturer and/or dealer of the hydraulic equipment, the symbols of the associated schemes vary in a smaller or a greater extent. The real reasons for the existence of these differences can only be assumed. According to some authors, companies want their drawings to differ from the hydraulic schema of competitors. Therefore, the most commonly used hydraulic symbols are presented in this paper.
{"title":"Hydraulic symbols: Part one: General symbols and symbols of measuring instruments and indicators","authors":"Dragana Petrović, V. Cerović","doi":"10.5937/POLJTEH1901045P","DOIUrl":"https://doi.org/10.5937/POLJTEH1901045P","url":null,"abstract":"Hydraulic power transfer and management systems are widely used in modern agriculture, especially in agricultural engineering and the associated processing industry. They can be very simple, but also extremely complex, when precise matching of the interaction of their components in real time is very difficult to controll and achieve. In addition, the designs of a number of hydraulic components is sufficiently complicated for detailed representation on the corresponding hydraulic installation. In all cases, analyzing the performance characteristics of components and the entire hydraulic system, as well as understanding the structure of the hydraulic system, is of great importance. One of the generally accepted ways to facilitate and speed up these processes is the application of schematic diagrams of hydraulic systems and their subcircuits. Officially, hydraulic symbols are defined by ISO industry standards. Therefore, ideally, all hydraulic schemes should be configured using universal graphic symbols. Unfortunately, this is not always the case in technical practice. Depending on the manufacturer and/or dealer of the hydraulic equipment, the symbols of the associated schemes vary in a smaller or a greater extent. The real reasons for the existence of these differences can only be assumed. According to some authors, companies want their drawings to differ from the hydraulic schema of competitors. Therefore, the most commonly used hydraulic symbols are presented in this paper.","PeriodicalId":281326,"journal":{"name":"Poljoprivredna tehnika","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126680916","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zlata Bracanović, V. Petrović, Branka Grozdanić, D. Borak
{"title":"The establishing of agricultural cooperative and their importance for the economy of the Republic of Serbia","authors":"Zlata Bracanović, V. Petrović, Branka Grozdanić, D. Borak","doi":"10.5937/POLJTEH1901031B","DOIUrl":"https://doi.org/10.5937/POLJTEH1901031B","url":null,"abstract":"","PeriodicalId":281326,"journal":{"name":"Poljoprivredna tehnika","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123840613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ivana Medojevic, D. Marković, V. Simonović, Aleksandra Joksimović, Jovana Rosić-Šakota
{"title":"The convolutional neural networks: Applications in precision agriculture","authors":"Ivana Medojevic, D. Marković, V. Simonović, Aleksandra Joksimović, Jovana Rosić-Šakota","doi":"10.5937/POLJTEH1901001M","DOIUrl":"https://doi.org/10.5937/POLJTEH1901001M","url":null,"abstract":"","PeriodicalId":281326,"journal":{"name":"Poljoprivredna tehnika","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128826612","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Djokić, R. Stanisavljević, D. Terzić, J. Milenković, V. Kozlov, R. Koprivica, A. Vuković
{"title":"Parameteres of efficiency of machines for seed processing of red clover and alfalfa","authors":"D. Djokić, R. Stanisavljević, D. Terzić, J. Milenković, V. Kozlov, R. Koprivica, A. Vuković","doi":"10.5937/POLJTEH1901010D","DOIUrl":"https://doi.org/10.5937/POLJTEH1901010D","url":null,"abstract":"","PeriodicalId":281326,"journal":{"name":"Poljoprivredna tehnika","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125258477","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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