scholarly journals The Influence of Indirect Air-Cooling Combined with Evaporative Cooling on Tomato Fruit Cooling Time and Temperature

2021 ◽  
pp. 69-75
Author(s):  
Sipho Sibanda ◽  
Tilahun Seyoum Workneh
Keyword(s):  
Ambient Temperature ◽  
Storage Temperature ◽  
Tomato Fruit ◽  
Evaporative Cooling ◽  
Climatic Conditions ◽  
Cooling Time ◽  
Small Scale ◽  
Air Cooling ◽  
Ambient Conditions ◽  
Fresh Tomato

This study developed a low cost and affordable to small-scale farmers’ indirect air-cooling combined with evaporative cooling (IAC+EC) system for storage of fruit and vegetables under both arid and hot; and humid and hot climatic conditions. Field heat from freshly harvested produce should be immediately removed through cooling to the desired storage temperature. The aim of this study was to determine the effectiveness of IAC+EC system in terms of the cooling time requirement of the fresh tomato fruit. A fresh tomato cooling experiment to remove field heat during the summer month of September in Pietermaritzburg was conducted for 36 hours where the IAC+EC system was compared to storage under ambient conditions. The results showed that 16 hours was required to reduce the flesh temperature of tomatoes to 16.5oC while the flesh temperature for tomatoes under ambient conditions followed the ambient temperature profile with time of storage. The IAC+EC system reduced and maintained the microenvironment air temperature inside the coolers to 16.50C- 19°C. The ambient temperature varied between 21 and 32°C. The results in this study are evidence that IAC+ EC system can be a choice to farmers, for cooling the fresh by reducing the field temperature after harvest.

Physiology of Oil Seeds. X. Seed Quality of Peanut Genotypes as Affected by Ambient Storage Temperature1

1992 ◽  
Vol 19 (2) ◽  
pp. 72-77 ◽  
Author(s):  
Darold L. Ketring
Keyword(s):  
Ambient Temperature ◽  
Seedling Growth ◽  
Seed Quality ◽  
Storage Temperature ◽  
Storage Conditions ◽  
Ambient Conditions ◽  
Ambient Storage ◽  
Wide Range ◽  
Genotype Diversity ◽  
Field Emergence

Abstract Proper storage of peanut (Arachis hypogaea L.) pods following drying is a critical step in maintenance of seed quality for the next planting season. The objective of this study was to examine the effect of ambient storage temperature (similar to farmers stock peanuts stored in warehouses) on seed germination and seedling vigor of selected peanut genotypes. Peanuts were grown in the field for three successive seasons. Pods were harvested, dried, and shelled. Seed samples were taken for storage under ambient conditions, humidity effects were eliminated by storing the seeds in plastic freezer bags in sealed containers. Seasons were: (1) 1986, 19 months storage at ambient temperature, (2) 1987, 7 months storage at ambient temperature, and (3) 1988, seeds without storage. When comparisons were made among genotypes within seasons, exposure to Season 1 conditions resulted in the least germination and seedling growth, but a wide range of genotype diversity occurred. Germination of seeds from Seasons 2 and 3 ranged from 81 to 98%, and significant differences in seedling growth occurred among genotypes. When comparisons were made across Seasons, the data indicated a significant storage effect, which resulted in different seed quality for individual genotypes. Usually field emergence was significantly different among genotypes and was highly correlated with germination for all seasons. Generally, emergence was negatively correlated with slow seedling growth and positively correlated with rapid seedling growth. Thus, for seeds of lower vigor (Seasons 1 and 2), rapid seedling growth was particularly critical for early, uniform emergence (10 DAP) in the field. Genotypes were significantly different in extent of seed quality reduction and field emergence both within and across storage periods. Genotype diversity to ambient storage conditions suggests there is genetic potential to improve longevity of seed quality during storage and enhance stability of field emergence.

scholarly journals The effect of calf jackets on the health, performance, and skin temperature of dairy origin beef calves

2019 ◽  
Vol 4 (1) ◽  
pp. 316-323 ◽  
Author(s):  
Naomi H Rutherford ◽  
Alan W Gordon ◽  
Gareth Arnott ◽  
Francis O Lively
Keyword(s):  
Ambient Temperature ◽  
Skin Temperature ◽  
Disease Incidence ◽  
Live Weight ◽  
Climatic Conditions ◽  
Ambient Conditions ◽  
Beef Calves ◽  
Calf Health ◽  
Health Performance ◽  
Humidity Index

Abstract Variations and extremities in climatic conditions can result in cold stress for dairy calves during the preweaning period. The objective of this study was to investigate the effect of calf jackets on the health, performance, and skin temperature of dairy-origin beef calves. This study took place in a designated calf rearing unit, spanned for a duration of 1 yr, and consisted of five batches of calves. Calves (30.9 ± 1.68 d of age; 55.9 ± 0.20 kg live weight) were assigned to one of four treatment groups on arrival at the rearing unit. Treatments consisted of control (no jacket), arrival (jacket for 2 wk postarrival), weight (jacket for a minimum of 2 wk and until 65 kg live weight), and wean (jacket until 5 d postweaning). Ambient conditions differed significantly (P < 0.001) during each of the five batches; batch 4 was the coldest with a mean ambient temperature of 6.16 °C. Significant differences were observed between the five batches for day 50 weight (P < 0.01) and disease incidence (P < 0.05). However, treatment had no significant effect on calf health or performance (P > 0.05) during any of the five batches. Skin temperature was significantly greater (P < 0.001) for calves wearing a jacket. Furthermore, there was a significant (P < 0.001) relationship between ambient temperature-humidity index and skin temperature for calves with and without a calf jacket. Therefore, although calf jackets had no benefit in terms of health or performance, they did act as a barrier to environmental conditions.

scholarly journals Efficiency of solar radiation conversion in photovoltaic panels

2018 ◽  
Vol 10 ◽  
pp. 02014 ◽  
Author(s):  
Sławomir Kurpaska ◽  
Jarosław Knaga ◽  
Hubert Latała ◽  
Jakub Sikora ◽  
Wiesław Tomczyk
Keyword(s):  
Solar Radiation ◽  
Ambient Temperature ◽  
Conversion Efficiency ◽  
Radiation Intensity ◽  
Radiation Energy ◽  
Climatic Conditions ◽  
Ambient Conditions ◽  
Photovoltaic Panels ◽  
Solar Radiation Intensity ◽  
Radiation Conversion

This paper included analysis the conversion efficiency in photovoltaic panels. The tests were done between February and June at a test stand equipped with three commonly used types of photovoltaic panels: poly- and monocrystalline silicon and with semi-conductive layer made of copper (Cu), indium (In), gallium (Ga) and selenium (Se) (CIGS). Five days of each month were selected for a detailed analysis. They were close to the so-called recommended day for calculations in solar power engineering. Efficiency, calculated as the yield of electrical energy in relation to solar radiation energy reaching the panels was made conditional upon solar radiation intensity and ambient temperature. It was found that as solar radiation intensity and ambient temperature increase, the efficiency of solar radiation conversion into electricity is reduced. Correlation dependence was determined for the test data obtained, describing temperature change of panels depending on climatic conditions. It was found that as panel temperature increases, the conversion efficiency is reduced. Within the tested scope of experiment conditions, the efficiency was reduced in the range between 20.1 and 22.8%. The authors also determined the average efficiency values in individual test months together with average ambient conditions of the environment where the process of solar radiation conversion took place.

Systematic Assessment of Combustion Turbine Inlet Air-Cooling Techniques

2005 ◽  
Vol 127 (1) ◽  
pp. 159-169 ◽  
Author(s):  
Abdalla M. Al-Amiri ◽  
Montaser M. Zamzam
Keyword(s):  
Air Temperature ◽  
Evaporative Cooling ◽  
Heat Rate ◽  
Climatic Conditions ◽  
Coefficient Of Performance ◽  
Air Cooling ◽  
Cooling Systems ◽  
Turbine Inlet ◽  
Wide Range ◽  
The Impact

The current study is centered on assessing the benefits of incorporating combustion turbine inlet air-cooling systems into a reference combustion turbine plant, which is based on a simple cycle under base load mode. Actual climatic conditions of a selected site were examined thoroughly to identify the different governing weather patterns. The main performance characteristics of both refrigerative and evaporative cooling systems were explored by examining the effect of several parameters including inlet air temperature, airflow-to-turbine output ratio, coefficient of performance (for refrigerative cooling systems), and evaporative degree hours (for evaporative cooling systems). The impact of these parameters was presented against the annual gross energy increase, average heat rate reduction, cooling load requirements and net power increase. Finally, a feasibility design chart was constructed to outline the economic returns of employing a refrigerative cooling unit against different prescribed inlet air temperature values using a wide range of combustion turbine mass flow rates.

scholarly journals DESEMPENHO DE UM SISTEMA DE RESFRIAMENTO EVAPORATIVO DO AR EM CASA-DE-VEGETAÇÃO

Irriga ◽  
2010 ◽  
Vol 15 (2) ◽  
pp. 140-150
Author(s):  
Antonio José Steidle Neto ◽  
SÉRGIO ZOLNIER
Keyword(s):  
Vapor Pressure ◽  
Air Temperature ◽  
Vapor Pressure Deficit ◽  
Cooling System ◽  
Evaporative Cooling ◽  
Climatic Conditions ◽  
Air Cooling ◽  
Cooling Efficiency ◽  
Growing Period ◽  
Air Cooling System

Este trabalho foi conduzido com o objetivo de analisar o desempenho de um sistema de resfriamento evaporativo do ar (tipo painel-exaustor) em casa-de-vegetação, ao longo do período diurno em dias com condições climáticas distintas. Foram realizadas medições de temperatura e umidade relativa do ar no interior e exterior de uma casa-de-vegetação durante o período de crescimento e desenvolvimento de tomateiros cultivados em substrato de areia. Verificou-se que as eficiências médias diárias de resfriamento evaporativo do ar variaram entre 74% e 81%. Os decréscimos máximos na temperatura do ar, imediatamente após a sua passagem pelo painel de celulose, foram de 8,2ºC e 11,4ºC. Observou-se ainda que, a eficiência de resfriamento do ar foi sensivelmente melhorada quando o déficit de pressão de vapor d'água do ar externo foi superior a 1,8 kPa.   UNITERMOS: déficit de pressão de vapor d'água do ar, temperatura do ar, eficiência de resfriamento evaporativo.     STEIDLE NETO, A. J.; ZOLNIER, S. EVAPORATIVE AIR COOLING SYSTEM PERFORMANCE IN A GREENHOUSE     2 ABSTRACT   This work aimed to analyze the performance of an evaporative air cooling system (pad-fan type) in greenhouse along daytime period in days with different climatic conditions. Air temperature and relative humidity measurements inside and outside of an greenhouse were made during the growing period of tomato plants cultivated in sand substrate. It was verified that the average daily evaporative cooling efficiency ranged from 74% to 81%. The maximum air temperature decrements, immediately after its passage through the cellulose pad, were 8.2°C and 11.4°C. It was also observed that the air cooling efficiency was sensitively improved when the vapor pressure deficit of the external air was higher than 1.8 kPa.   KEYWORDS: vapor pressure deficit, air temperature, evaporative cooling efficiency.  

Inlet Air Cooling Methods for Gas Turbine Based Power Plants

2004 ◽  
Author(s):  
E. Kakaras ◽  
A. Doukelis ◽  
A. Prelipceanu ◽  
S. Karellas
Keyword(s):  
Gas Turbine ◽  
Power Output ◽  
Gas Turbines ◽  
Power Plants ◽  
Evaporative Cooling ◽  
Climatic Conditions ◽  
Combined Cycle ◽  
Air Cooling ◽  
Cooling Systems ◽  
Cooling Methods

Power generation from gas turbines is penalised by a substantial power output loss with increased ambient temperature. By cooling down the gas turbine intake air, the power output penalty can be mitigated. The purpose of this paper is to review the state of the art in applications for reducing the gas turbine intake air temperature and examine the merits from integration of the different air-cooling methods in gas turbine based power plants. Three different intake air-cooling methods (evaporative cooling, refrigeration cooling and evaporative cooling of pre-compressed air) have been applied in two combined cycle power plants and two gas turbine plants. The calculations were performed on a yearly basis of operation, taking into account the time-varying climatic conditions. The economics from integration of the different cooling systems were calculated and compared.

Gas Turbine Power Boosting: Evaporative Cooling

2010 ◽  
Author(s):  
S. Brusca ◽  
R. Lanzafame
Keyword(s):  
Mathematical Model ◽  
Ambient Temperature ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Evaporative Cooling ◽  
Maximum Load ◽  
Ambient Conditions ◽  
Critical Temperatures ◽  
Boosting Technique ◽  
The Impact

It is well known that gas turbines performance depend on ambient conditions. In particular, power production decreases when ambient temperature increases. It is possible to restore standard performance while running at critical temperatures using a power boosting technique such as evaporative cooling. The present paper deals with analysis of gas turbines power boosting by means of an evaporative cooling technique. In order to study the impact of the technique on gas turbine performance, a mathematical model of a General Electric MS6001FA gas turbine has been implemented using GateCycle software. The mathematical model was calibrated and tested using real gas turbine data for different running conditions. Test results show that the model is able to simulate engine behavior in all considered conditions with low errors. Parametric analysis in function of ambient conditions at maximum load was carried out. It was imposed a specific value of artificial air humidity using real ambient temperature and pressure. Thus, performance analysis of gas turbine running was carried out.

Thermo-Economic Analysis of Inlet Air Conditioning Methods of a Cogeneration Gas Turbine Plant

2002 ◽  
Author(s):  
M. Nixdorf ◽  
A. Prelipceanu ◽  
D. Hein
Keyword(s):  
Gas Turbine ◽  
Air Conditioning ◽  
Thermal Power ◽  
Evaporative Cooling ◽  
Ambient Air ◽  
Air Cooling ◽  
Ambient Conditions ◽  
Reference Case ◽  
Turbine Plant ◽  
Gas Turbine Plant

The purpose of this work is to investigate the benefits of some different ambient air conditioning methods for reducing the gas turbine intake air temperature in order to enhance the gas turbine power. As a reference case the combined heat and power plant of the campus area of the Technische Universita¨t Mu¨nchen in Garching is considered, which is equipped with an Allison KH501 Cheng Cycle gas turbine. Three novel technical possibilities of ambient air cooling and power augmentation are shown in detail (desiccant dehumidification and evaporative cooling, absorption chiller unit with air cooler, evaporative cooling at increased inlet air pressure). Based on site ambient conditions and measured yearly load lines for heat and electrical power connected with actual cost functions, the potential economic savings are worked out for the different technical modifications using ambient air cooling for power augmentation of the gas turbine plant. The economic operation lines for power and heat, supplied by the modified gas turbine plant, are calculated by a cost optimization system. The results are compared based on investment costs and economic savings by the extended annual electrical and thermal power production of the modified gas turbine plant.

scholarly journals Thermodynamic Analysis of the Air-Cooled Transcritical Rankine Cycle Using CO2/R161 Mixture Based on Natural Draft Dry Cooling Towers

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3342 ◽  
Author(s):  
Zhou ◽  
Tang ◽  
Zhang ◽  
Li
Keyword(s):  
Ambient Temperature ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Small Scale ◽  
Low Grade ◽  
Air Cooling ◽  
Cooling Towers ◽  
Natural Draft ◽  
Dry Cooling ◽  
Transcritical Rankine Cycle

Heat rejection in the hot-arid area is of concern to power cycles, especially for the transcritical Rankine cycle using CO2 as the working fluid in harvesting the low-grade energy. Usually, water is employed as the cooling substance in Rankine cycles. In this paper, the transcritical Rankine cycle with CO2/R161 mixture and dry air cooling systems had been proposed to be used in arid areas with water shortage. A design and rating model for mixture-air cooling process were developed based on small-scale natural draft dry cooling towers. The influence of key parameters on the system’s thermodynamic performance was tested. The results suggested that the thermal efficiency of the proposed system was decreased with the increases in the turbine inlet pressure and the ambient temperature, with the given thermal power as the heat source. Additionally, the cooling performance of natural draft dry cooling tower was found to be affected by the ambient temperature and the turbine exhaust temperature.

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