Development of a Stockpile Heated and Ambient Air Dryer (SHAD) for Freshly Harvested Almonds

2021 ◽  
Vol 37 (3) ◽  
pp. 417-425
Author(s):  
Ismael Kilinya Mayanja ◽  
Michael C Coates ◽  
Franz Niederholzer ◽  
Irwin R Donis-González
Keyword(s):  
Ambient Air ◽  
Bare Soil ◽  
Quality Parameters ◽  
Extraction Rate ◽  
Coefficient Of Performance ◽  
Drying Methods ◽  
List Type ◽  
Moisture Extraction ◽  
Internal Cavities ◽  
Air Dryer

HighlightsAlmonds are conventionally sun-dried on the orchard floor. Collection and removal of dried nuts from the orchard generates significant dust.Almonds were dried on-farm directly from the almond tree eliminating field drying.SHAD dryer uses a combination of heated and ambient air to dry almonds in a stockpile.The dryer has a SMER of 0.64 kg/kWh, MER of 1.02 kg/h, and COP of 1.33.Abstract. Dust generated by farming activities is a safety hazard to farmworkers and an environmental contaminant. During the almond (Prunus dulcis) harvest in California, dust is primarily generated by the mechanized movement of almonds disturbing the bare soil of the orchard floor, during the sun-drying, windrowing process, and as they are transferred into trucks for transport to processing facilities. Off-ground dust-less harvesting will only be achieved when the almond industry adopts feasible mechanical drying methods. Therefore, a stockpile heated and ambient air dryer (SHAD) was developed to determine the feasibility of dehydrating almonds (Var. ‘Monterey’). A stockpile containing 4,155 kg of almonds was created and almonds were dehydrated from their initial 12.6% almond kernel dry-basis moisture content (MCdb) to final MCdb of 6.04%. Drying was achieved as a combination of heated air at a temperature of 55°C in the drying plenum with airflow of 0.078 m3/s per m3 of fresh almonds. After drying, almond quality parameters were measured, including damage by molds or decay, insect injury, and presence of internal cavities. Drying energy consumption, cost, and performance indicators were also determined. The differences in MCdb between the bottom, middle, and top layers of the almond stockpile were significant (p = 0.05). Post-hoc Tuckey test was conducted which indicated that the MCdb in the top layer was significantly lower than almond MCdb in the middle and bottom layers. Results showed that damage by molds or decay, insect injury, and internal cavities were 1.81%, 0%, and 1.77%, respectively, after drying. Therefore, the overall almond quality was not compromised. The drying process cost $11.65 per tonne of the initial weight of almonds with a Specific Moisture Extraction Rate (SMER) of 0.64 kg/kWh, Moisture Extraction Rate (MER) of 1.02 kg/h, and a Coefficient of Performance (COP) of 1.33. Comparison with other dryers in the literature shows that SMER and MER were within limits. However, a low COP was observed. Keywords: Dust, Energy, Postharvest, Stockpile drying, Tree nut.s

scholarly journals Performance Analysis of Heat Pump Dryer with Unit-Room in Cold Climate Regions

Energies ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 3125 ◽  
Author(s):  
Yuan ◽  
Lin ◽  
Mao ◽  
Li ◽  
Yang ◽  
...  
Keyword(s):  
Heat Pump ◽  
Ambient Air ◽  
Open Loop ◽  
Cold Climate ◽  
Coefficient Of Performance ◽  
Ambient Conditions ◽  
Total Energy Consumption ◽  
Ambient Temperatures ◽  
Moisture Extraction ◽  
Modelling System

This study presents the development and evaluation of a novel partially open-loop heat pump dryer with a unit-room (HPDU). The unit-room was designed to enable the ambient air to be mixed with the return air, thereby reducing the influence of the ambient air on the system performance, while maintaining a high system thermal efficiency. A modelling system for the HPDU was developed and validated based on a real-scale experimental study. By using the modelling system, the system characteristics under different ambient conditions and bypass factors were analyzed. The energy benefit of the proposed HPDU was quantified through a comparative study with a closed-loop heat pump dryer (CHPD). It is evident that a maximal specific moisture extraction rate (SMER) and a minimal total energy consumption (TEC) existed when changing the bypass factor of the HPDU under certain ambient temperatures. Compared to the CHPD, the coefficient of performance (COP) of the HPDU increased by up to 39.56%, presenting a significant energy benefit for the application of HPDU.

scholarly journals Simulation and Experimental Study on Drying Process of the Household Gas Clothes Dryer

2019 ◽  
Vol 2019 ◽  
pp. 1-17
Author(s):  
Xiao-mei Huang ◽  
Yi Zhao ◽  
Hui-qing Liu
Keyword(s):  
Ambient Temperature ◽  
Gas Flow ◽  
Operating Time ◽  
Ambient Air ◽  
Dry Mass ◽  
Extraction Rate ◽  
Drying Process ◽  
Drying Time ◽  
Clothes Dryer ◽  
Moisture Extraction

This paper analyzed the drying process of the household gas clothes dryer (GCD) based on the principle of heat and mass transfer. The drying models in three scenarios were established: natural gas burned in combustion chamber, ambient air mixed with exhausted gas in hot gas duct, and clothes were dried in the drying drum. The simulation of the drying process was performed on MATLAB software. And the effectiveness of the drying model was verified by comparison with experiment results. The effects of gas flow rate, dry mass of clothes, ambient temperature, ambient humidity, textile type, and moisture extraction rate (MER) on the performance of dryers were studied. This paper provided a theoretical basis for the design and optimization of GCDs. It was found that the drying time of the gas clothes dryer was mostly affected by the gas flow and dry mass of clothes, and the specific moisture extraction rate (SMER) was mostly affected by the ambient temperature and relative humidity. The nylon clothes have the fastest MER and the smallest SMER. Moreover, reducing operating time in falling-rate drying period can improve energy efficiency.

scholarly journals Design And Analysis of Flat Plate Solar Air Dryer

2020 ◽  
Vol 7 (1) ◽  
pp. 37-40
Author(s):  
Arunprasad S ◽  
Saravanan P ◽  
Arulraj R
Keyword(s):  
Solar Radiation ◽  
Solar Energy ◽  
Flat Plate ◽  
Basic Function ◽  
Insulation Material ◽  
Ansys Software ◽  
Heated Air ◽  
Moisture Extraction ◽  
Air Dryer ◽  
Drying Chamber

Solar dryers are equipment and using solar energy for drying substances, especially food. There are two common types of solar dryers: Direct & indirect. This is a dryer type in which the product to be dried directly absorbs the solar radiation. It is also referred to as a natural convection cabinet dryer, because the solar radiation falls directly on the surface; the product quality is reduced. Heated air from the drying chamber is blown through. A solar dryer's basic function is to heat air with solar energy to a constant temperature, which enables the moisture extraction from crops within a drying chamber. The main objective of flat plate solar air dryer model based on without tray & with tray chamber in Creo parametric software & computational fluid dynamics in Ansys software. Generally, solar air dryer is heat loss is possible, so it’s reduced with help of insulation material (glass wool & polyurethane). To predict the temperature difference in various air flow with insulation material. Furthermore, choose the better insulation material & difference between with & without tray chamber.

scholarly journals Cutting Oxygen Production-Related Greenhouse Gas Emissions by Improved Compression Heat Management in a Cryogenic Air Separation Unit

2021 ◽  
Vol 18 (19) ◽  
pp. 10370
Author(s):  
Miroslav Variny ◽  
Dominika Jediná ◽  
Miroslav Rimár ◽  
Ján Kizek ◽  
Marianna Kšiňanová
Keyword(s):  
Power Consumption ◽  
Greenhouse Gas Emissions ◽  
Greenhouse Gas ◽  
Ambient Air ◽  
Air Separation ◽  
Oxygen Production ◽  
Gas Emissions ◽  
Separation Unit ◽  
Air Separation Unit ◽  
Air Dryer

Oxygen production in cryogenic air separation units is related to a significant carbon footprint and its supply in the medicinal sphere became critical during the recent COVID-19 crisis. An improved unit design was proposed, utilizing a part of waste heat produced during air pre-cooling and intercooling via absorption coolers, to reduce power consumption. Variable ambient air humidity impact on compressed air dryers’ regeneration was also considered. A steady-state process simulation of a model 500 t h−1 inlet cryogenic air separation unit was performed in Aspen Plus® V11. Comparison of a model without and with absorption coolers yielded an achievable reduction in power consumption for air compression and air dryer regeneration by 6 to 9% (23 to 33 GWh year−1) and a favorable simple payback period of 4 to 10 years, both depending on air pressure loss in additional heat exchangers to be installed. The resulting specific oxygen production decrease amounted to EUR 2–4.2 t−1. Emissions of major gaseous pollutants from power production were both calculated by an in-house developed thermal power plant model and adopted from literature. A power consumption cut was translated into the following annual greenhouse gas emission reduction: CO2 16 to 30 kilotons, CO 0.3 to 2.3 tons, SOx 4.7 to 187 tons and NOx 11 to 56 tons, depending on applied fossil fuel-based emission factors. Considering a more renewable energy sources-containing energy mix, annual greenhouse gas emissions decreased by 50 to over 80%, varying for individual pollutants.

scholarly journals Theoretical Analysis of a Single-Stage Gas-fired Ejector Heat Pump Water Heater

2021 ◽  
pp. 1-28
Author(s):  
Jeremy Spitzenberger ◽  
Pengtao Wang ◽  
Laith Ismael ◽  
Hongbin Ma ◽  
Ahmad Abuheiba ◽  
...  
Keyword(s):  
Heat Pump ◽  
Thermal Energy ◽  
Ambient Air ◽  
Single Stage ◽  
Coefficient Of Performance ◽  
Water Heater ◽  
Pump System ◽  
Heat Pump System ◽  
Heating Capacity ◽  
Condenser Temperature

Abstract Ejector driven systems have the ability to operate at high efficiencies, utilizing recycled thermal energy as a power source. For a typical ejector heat pump system, the increase of the condenser temperature reduces the coefficient of performance (COP). In addition, if the condenser temperature is higher than the critical temperature, the ejector may not function. In this situation, the condenser temperature must be reduced, and an additional heater will be utilized to heat the production water from the condenser temperature to the desired temperature. In this investigation, a single-stage gas-fired ejector heat pump (EHP) is investigated and thermodynamically modeled in order to optimize the system COP for the purpose of heating water by utilizing the thermal energy from the ambient air. The effects of the high-temperature evaporator (HTE) and low-temperature evaporator (LTE) temperatures on the ejector critical back pressure and the EHP system performance are examined for a HTE temperature range of 120-180 °C and LTE temperatures of 15.5, 17.5, and 19.5 °C. Results show that an optimized COP of the EHP system exists which depends on HTE and LTE temperatures, primary nozzle throat diameters. In addition, it is found that the EHP COP is independent of the ejector COP. From this investigation a maximum EHP COP of 1.31 is able to be achieved for a HTE temperature of 160 °C and a LTE temperature of 19.5 °C with a total heating capacity of 15.98 kW.

Ambient Air Quality Monitoring Studies in Four Specific Location of Tamilnadu, India

2019 ◽  
pp. 677-683
Author(s):  
Mageshkumar P ◽  
Ramesh S ◽  
Angu Senthil K
Keyword(s):  
Air Quality ◽  
Quality Index ◽  
High Volume ◽  
Ambient Air ◽  
Quality Parameters ◽  
Air Quality Index ◽  
Gaseous Pollutants ◽  
Ambient Air Quality ◽  
Air Sampler

A comprehensive study on the air quality was carried out in four locations namely, Tiruchengode Bus Stand, K.S.R College Campus, Pallipalayam Bus Stop and Erode Government Hospital to assess the prevailing quality of air. Ambient air sampling was carried out in four locations using a high volume air sampler and the mass concentrations of PM10, PM2.5, SO2, NOX and CO were measured. The analyzed quality parameters were compared with the values suggested by National Ambient Air Quality Standards (NAAQS). Air quality index was also calculated for the gaseous pollutants and for Particulate Matters. It was found that PM10 concentration exceeds the threshold limits in all the measured locations. The higher vehicular density is one of the main reasons for the higher concentrations of these gaseous pollutants. The air quality index results show that the selected locations come under moderate air pollution.

scholarly journals Comparison of Supercritical CO2-Drying, Freeze-Drying and Frying on Sensory Properties of Beetroot

Foods ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1201
Author(s):  
Nikola Tomic ◽  
Ilija Djekic ◽  
Gerard Hofland ◽  
Nada Smigic ◽  
Bozidar Udovicki ◽  
...  
Keyword(s):  
Supercritical Co2 ◽  
Freeze Drying ◽  
Sensory Quality ◽  
Quality Parameters ◽  
Acceptance Testing ◽  
Drying Methods ◽  
Promising Alternative ◽  
Supercritical Co2 Drying ◽  
Negative Effect ◽  
Drying Technology

The aim of this study was to compare the sensory quality and acceptance of dried ready-to-eat beetroot snacks as a result of different drying methods applied: supercritical CO2-drying (scCO2-drying), frying, and freeze-drying. Descriptive sensory analysis, quality rating (10 assessors), and consumer acceptance testing (n = 102) were performed. Mean overall quality scores within the range of “very good” quality were found only in non-precooked scCO2-dried samples which were characterized by typical magenta color, low level of shape and surface deformations, pronounced brittleness and crispiness, and good rehydration during mastication. The other samples were in the range of “good” quality. The pre-cooking step before scCO2-drying negatively influenced the sensory quality parameters, particularly appearance. Around 60% of tested consumers showed a preference for the fried and non-precooked scCO2-dried samples. The drivers of liking were mostly related to the characteristics of the product, which was salted, fried, and crispy, with an oily and overburnt flavor, i.e., the product most similar to commercial potato chips products. Freeze-drying had a negative effect primarily on appearance and flavor. According to the sensory evaluation conducted, direct scCO2-drying without a pre-cooking step showed itself as a promising alternative drying technology in the production of dried beetroot snacks.

scholarly journals Numerical Simulation of Meteorological Conditions and Air Quality above Tomsk, West Siberia

Atmosphere ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1148
Author(s):  
Alexander Starchenko ◽  
Elena Shelmina ◽  
Lubov Kizhner
Keyword(s):  
Air Quality ◽  
West Siberia ◽  
Ambient Air ◽  
Quality Parameters ◽  
Meteorological Conditions ◽  
Observation Data ◽  
Near Surface ◽  
Calculation Results ◽  
Simulation Results ◽  
Calm Wind

This paper presents the simulation results of meteorological and air quality parameters for the Siberian city of Tomsk predicted by mesoscale meteorological and chemical transport models. Changes in the numerically predicted wind velocity fields, temperature, and concentration of major air pollutants were modelled in detail for the selected dates, when anticyclonic weather with cloud free and calm wind conditions was observed in Tomsk. The simulation results have shown that stable or neutral atmospheric stratification with light wind and low ambient air temperature (−30, −20 °C) are the most unfavorable meteorological conditions leading to the near surface pollutants accumulation. The numerical calculation results were compared with observation data from the Joint Use Center (JUC) “Atmosphere” of V.E. Zuev Institute of Atmospheric Optics (IAO) and showed good agreement.

A Field Study of a Low-Flow Internally Cooled/Heated Liquid Desiccant Air Conditioning System: Quasi-Steady and Transient Performance

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Ahmed H. Abdel-Salam ◽  
Chris McNevin ◽  
Lisa Crofoot ◽  
Stephen J. Harrison ◽  
Carey J. Simonson
Keyword(s):  
Air Conditioning ◽  
Field Performance ◽  
Ambient Air ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Low Flow ◽  
Transient Field ◽  
Liquid Desiccant ◽  
Internally Cooled ◽  
Steady Performance

The field performance of a low-flow internally cooled/heated liquid desiccant air conditioning (LDAC) system is investigated in this paper. The quasi-steady performance (sensible and latent heat transfer rates, coefficient of performance (COP), and uncertainties) of the LDAC system is quantified under different ambient air conditions. A major contribution of this work is a direct comparison of the transient and quasi-steady performance of the LDAC system. This paper is the first to quantify the importance of transients and shows that, for the environmental and operating conditions in this paper, transients can be neglected when estimating the energy consumption of the LDAC system. Another major contribution of this work is the development and verification of a new method that quantifies (with acceptable uncertainties) the quasi-steady performance of a LDAC system from transient field data using average data.

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