Hot Moist Air Research Articles

Current status and management of sugarcanesmut disease in North India

Sugarcane an important cash crop suffers from several fungal, bacterial, phytoplasmal and viral diseases. Of the fungal diseases, smut had been a major constraint to sugarcane production in most of the sugarcane growing tracts of the country. The disease is caused by fungus Sporisoriumscitamineum (Syn: Ustilago scitaminea).Primary transmission of the disease takes place trough infected setts. Earlier this disease was kept under control through heat therapy (Aerated steam therapy /moist hot air treatment) of seed canes by the sugar mills and sugarcane research centers. However, since last couple of years, sett treatment practice has been stopped and smut incidence increased by many folds. To know the current scenario of sugarcane diseases in the subtropical region, authors surveyed the reserved areas of 44 sugar mills in Haryana, Punjab, Uttar Pradesh, Bihar and Uttrakhand states during 2010-2019 crop seasons regularly. In Haryana, smut prevails as major disease in most of the sugar mills and its incidence is increasing rapidly. The disease incidence ranged from 1.0 to 40.0% in ratoons and traces to 9.0% in plant crops of varieties viz. Co 0238, Co 89003, CoH 116, CoH 119, CoH 150, CoH 152, CoH 156, CoH 160, CoJ 85, CoJ 88 and CoS 8436. In Shahabad area most of the fields of variety CoH 160 had severe smut incidence i.e. up to 40.0% in ratoon and 9.0% on plant crops. Similarly in the varieties Co 0238, Co 89003 and CoJ 88 cultivated under Punjab, traces to 11.0% incidence in ratoon and up to 5.0% in plant crops was found. Further, in western UP occurrence of smut was moderate to 6.5% in ratoon and traces to 1.5% in plant crops of cultivated varieties. The maximum disease incidence (T-2.5%) was noted in Harinagar (Bihar) on variety CoSe98231, whereas, under Laksar (Uttrakhand) it observed to a tune of 4.5% and 6.0% on varieties CoSe 03234 and CoSe 01434, respectively. In the light of observations recoded over the period, advisories were issued regularly to the sugar mills for its prevention and farmers of the state have adopted smut management practices i.e. roguing of smut whips followed by spray of Propiconazole 25EC @ 0.1%. Farmers and sugar mill officials of the state have been advised to adopt seed cane treatment practices with Sett Treatment Device, recently developed by ICAR-SBI, Coimbatore to combat this disease. The Haryana sugar Federation is also advised to promote sett treatment practice in the state. Since last four years all the Co-operative sugar mills have been running tractor driven sett treatment units for seed cane treatment at farmer fields to manage sett borne diseases. Since smut has emerged as a serious disease, sugar industry should take up the disease management in a systematic way to sustain sugarcane cultivation in the region and also to prevent buildup of disease epidemics.

Influence of hormetic heat treatment on quality and phytochemical compounds of broccoli florets during storage

The effect of moist hot air treatment applied to broccoli florets was studied in order to maintain quality and phytochemical compounds during postharvest storage at 4°C. Exposure to hormetic heat doses of 41°C for 180min (low temperature, LT) and 47°C for 12min (high temperature, HT) delayed yellowing for 21 d compared with non-heated florets that yellowed after 14 d. Chlorophyll content was also higher in florets treated with both the LT and HT heat treatments. The respiration rate of heat-treated broccoli was significantly higher immediately after heat treatments, being 10-times greater in LT-treated and 15-times greater in HT-treated florets on day 0 when compared with the control florets. However, after 7 d of storage differences were not significant, even though respiration rates were lower in treated broccoli after 21 d of storage compared with non-heated florets. Off-odors were also detected in HT-treated broccoli. Titers of indole-type glucosinolates were significantly enhanced by both heat treatments, while the glucoraphanin content of florets only increased with the HT treatment. A similar pattern was observed with gene expression, where overexpression of tryptophan N-hydroxylase (CYP79B3) was greater than the expression of dihomomethionine N-hydroxylase (CYP79F1) in heat-treated broccoli florets. Titers of hydroxy-cinnamic acids of florets were increased by both heat treatments. The total antioxidant capacity was significantly enhanced by the HT treatment. Similarly, overexpression of coumarate ligase (CoL), chalcone synthase (CHS) and phenylalanine N-hydroxylase (CYP79A2) was triggered by the HT treatment. The results indicate hormetic heat treatments can enhance the content of phytochemicals in broccoli florets during storage. However, the application of heat at 41°C (LT) was superior to the HT treatment in maintaining quality, although the enhancement of phytochemicals was less.

Two-dimensional mathematical model for simulation of the drying process of thick layers of natural materials in a conveyor-belt dryer

This paper presents the mathematical model and numerical analysis of the convective drying process of thick slices of colloidal capillary-porous materials slowly moving through conveyor-belt dryer. A flow of hot moist air was used as drying agent. The drying process has been analyzed in the form of a 2-D mathematical model, in two directions: along the conveyor and perpendicular on it. The mathematical model consists of two non-linear differential equations and one equation with a transcendent character and it is based on the mathematical model developed for drying process in a form of a 1-D thin layer. The appropriate boundary conditions were introduced. The presented model is suitable for the automated control of conveyor-belt dryers. The obtained results with analysis could be useful in predicting the drying kinetics of potato slices and similar natural products.

Feasibility of drying system using waste heat as the heating source

In this study, a wastewater heat pump system was proposed and its thermal performance was analyzed. The proposed system includes two evaporators: an air-source evaporator and a water-source evaporator. The air-source evaporator absorbs heat from the moist hot air which exhaust from the drying oven. The water-source evaporator absorbs heat from the waste water, while the waste water recovers heat from the mechanical energy, which was produced by cutting and polishing in stone production. The thermodynamic model was developed to evaluate the performance of the proposed system. The energetic analysis was carried out to investigate the influences of the temperature of fresh air. The results show significantly higher energy efficiency, compact-sized and energy-saving compared with the system which uses air as the heat source. Among the seven of alternative refrigerants (R152a, R123, R1234yf, R1234ze, R600a, R22 and R600) investigated, R123 was suggested to be used in this heat pump for its high heating efficiency, inflammable, very low ODP(Ozone Depletion Potential) and GWP(Global warming potential).

Sanitation of olive plants infected by Verticillium dahliae using heat treatments

Verticillium wilt, caused by the fungus Verticillium dahliae, is currently the most important disease affecting olive in the Mediterranean basin. There are no effective treatments for controlling this disease. The use of infected nursery stocks has largely contributed to the spread of the pathogen, and therefore the development of treatments to preventively sanitize the propagation stock is critical in the nursery industry. This study describes novel techniques to achieve this aim. The effects of several temperature–exposure time combinations were evaluated: (i) the survival of pathogen on culture medium (PDA); (ii) the pathogen viability on infected shoots and plants; (iii) the vegetative growth of plants of several cultivars; and (iv) the rooting ability of cuttings. The colonies of the pathogen growing in PDA were killed after 8 h and 60 min of exposure at 40 and 47°C, respectively. Temperatures ≥42°C for at least 2 h were lethal for the pathogen infecting the shoots. Likewise, moist hot air treatments at 42–44°C for 6–12 h eradicated the pathogen, without compromising the viability of the plants. Five olive cultivars were also evaluated and classified according to their thermotolerance as follows: sensitive (Chiquitita), moderately sensitive (Koroneiki, Frantoio and Picual) and heat tolerant (Arbequina). However, the optimized sanitation methods were applicable to all of the cultivars. Finally, heat treatments were applied to unrooted cuttings, which severely affected their rooting ability. Thus, this study developed a hot air treatment to produce V. dahliae‐free olive nursery plants.

SIMULATION OF THE CALCIUM CHLORIDE AQUEOUS SALT SOLUTION SPRAY REGENERATION PROCESS

The present work is a simulation of spray regeneration of liquid desiccant aqueous solution using three-dimensional computational fluid dynamic software (CFX-10). This simulation involved the spray evaporation of calcium chloride aqueous salt solution, as a liquid desiccant, into hot moist air. Liquid desiccants have a unique mass transfer direction that depends on the value of the liquid desiccant vapor pressure to air vapor pressure. Therefore, a FORTRAN subroutine was designed and added to the CFX software, which dealt with the rate of mass transfer between the desiccant liquid and the hot moist air. Additionally, the effect of the spray evaporation parameters was investigated. To validate the numerical CFX work, an experimental test rig was designed and built, and a few experimental results were obtained. It was found that the values of the injected droplet diameter size, spray angle, hot air temperature, and spray injection speed had an important role in the liquid desiccant regeneration process. Finally, the CFX software with an additional subroutine succeeded in simulating the spray evaporation of calcium chloride aqueous salt solution.

A mathematical model and simulation of the drying process of thin layers of potatoes in a conveyor-belt dryer

This paper presents a mathematical model and numerical analysis of the convective drying process of small particles of potatoes slowly moving through the flow of a drying agent - hot moist air. The drying process was analyzed in the form of a one-dimensional thin layer. The mathematical model of the drying process is a system of two ordinary nonlinear differential equations with constant coefficients and an equation with a transcendent character. The appropriate boundary conditions of the mathematical model were given. The presented model is suitable in the automated control. The presented system of differential equations was solved numerically. The analysis presented here and the obtained results could be useful in predicting the drying kinetics of potatoes and similar natural products in a conveyor-belt dryer.

Buoyancy Driven Turbulence of Moist Air

In the present experiment we study turbulent moist air convection, where the turbulence is buoyancy driven and characterized by gradient Rayleigh number g(1/ρ0)(Δρ/l)d4/αν ∼ 108, in a square tube of aspect ratio 8. Hot moist air is provided at the bottom of the tube, while the top of the tube is open and is exposed to cold air reservoir. In the statistically steady state, a constant temperature gradient of −6.7 0C/m is obtained in the tube excluding some distance from the tube ends. Away from the tube ends width of the tube d is found to be relevant length scale indicating homogeneity of turbulence in the axial direction. Temperature profile is obtained from measurements. Calculations are shown that explain some features of the temperature curve. Heat fluxes are estimated.

Effect of pre-storage heat treatment on enzymological changes in peach.

Peach (Prunus persica (L.) Batsch) fruit was subjected to hot water and moist hot air treatment at varying temperatures. The activities of polyphenoloxidase (PPO) and polygalacturonase (PG) were monitored during storage for 0, 3 and 6 days. PPO activity decreased in all treatments during storage. This decrease was more in hot water treated fruits than in hot air. PPO activity decreased with the increase in treatment duration. However, the PG activity increased in heat treated fruits as well as control. This increase was more in mild heat treatments as compared to severe heat treatment. Both polyphenol and pectin contents decreased during storage in both heat treatments.

Energy and exergy analyses of an industrial wood chips drying process

In this study, a comprehensive thermodynamic investigation through energy and exergy analyses is conducted to assess the performance of an industrial chips drying process and study how its operating conditions and efficiency can be improved further. In this regard, energy and exergy efficiencies are evaluated with the actual thermodynamic data available, as obtained from the factory, in Turkey. Energy and exergy efficiencies of the drum drying system (DDS) are found as 34.07% and 4.39%, respectively. The analysis results show that exergy efficiency is less than energy efficiency. The main reason of this low exergy efficiency for this drying process is high exergy destruction, as 41.5% of input exergy value. Energy can be recovered via an economizer from hot moist air leaving from the system. If stack gas temperature decreases from 130 to 90°C, regain energy and exergy values are to be 51 976 and 8162 kW, respectively. These recovered potentials can be used for district heating system in winter season and for district cooling system in summer season by using absorption cooling system. Energy and exergy efficiency values can be increased to 93.15 and 43.08%, respectively, by incorporating a heat exchanger into the system. Copyright The Author 2009. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org, Oxford University Press.

Controlling White Leaf Disease (WLD) Incidence of Sugarcane by Heat Therapy

An experiment was conducted to find out the effect of heat therapy on germination and white leaf disease incidence of sugarcane at Sreepur, Gazipur, Bangladesh. Germination was significantly increased in moist hot air treatment (MHAT) treated plot. No white leaf disease was found in MH,AT at 540C for 4 h, 3 h and 2.30 h treated settlings. Similarly, millable cane and cane yield were positively affected by heat therapy. Heat therapy with MHATand hot water treatment (HUT) performed better in increasing sugarcane yield compared to control. Keywords: Moist hot air treatment, hot water treatment, white leaf disease

In vitro production of Indian citrus ringspot virus (ICRSV) free Kinnow plants employing thermotherapy coupled with shoot tip grafting

Indian citrus ringspot virus (ICRSV) is known to cause serious disease problem in Kinnow (Citrus nobilis Lour × C. deliciosa Tenora) plants. This work reports the elimination of ICRSV by using thermotherapy coupled with shoot tip grafting in vitro. Nodal segments from infected mother plants (indexed by indirect ELISA and RT-PCR) were treated both in water bath and moist hot air at different temperatures viz. 40, 45 and 50°C for 30, 60 and 120 min and cultured on MS medium containing 2-iP (1 mg/l) and malt extract (800 mg/l). Shoot tips were excised from the nodal sprouts and grafted on to rough lemon (C. jambhiri) rootstock under aseptic conditions. Water bath treatment was found to be more effective as compared to moist hot air treatment as maximum number of ICRSV free plants (36.84%) were obtained by grafting the tips (0.7 mm) taken from the nodal segments treated at 50°C in water bath for 2 h. In an alternate treatment regime, 1-year-old infected plants were kept at various temperatures viz.36, 38 and 40°C in a thermotherapy chamber. Maximum of 60% ICRSV free plants were obtained by grafting the tips (0.7 mm) from the plants placed at 40°C followed by the plants placed at 38°C (59.09%) and the least was observed in case of the plants placed at 36°C (40.74%). Only those plants/plantlets were considered virus free, which showed negative reaction both in Indirect ELISA and RT-PCR.

EFFECT OF POSTHARVEST HOT AIR AND FUNGICIDE TREATMENTS ON THE QUALITY OF ‘MARADOL’ PAPAYA (CARICA PAPAYA L.)

ABSTRACTPapaya (Carica papaya L.) fruit is very perishable with a maximum postharvest life of 4 weeks. The effect of forced moist (100% RH) or dry (50%) hot air with or without Thiabendazole (TBZ at 1.2 g active ingredient/L) on the chilling injury (CI), fungi development and quality of ‘Maradol’papaya fruit stored at 5C or 20C for up to 42 days was investigated. Moist hot air at 48.5C or 50C for 4 h caused fruit injury. Dry air at 48.5C for 4 h, alone or in combination with TBZ, decreased CI intensity and fungi development, and the best effect was achieved by combining dry heat treatment and TBZ, without causing negative effects on fruit quality and without causing heat injury. Hot air treatment, especially in combination with TBZ, decreased growth of inoculated Colletotrichum gloeosporioides. Trehalose was not detected in papaya, probably due to the presence of trehalase. Hot water treatment, with or without TBZ, did not cause any negative effect on the content of β‐carotene and lycopene.

Effects of heat treatment on postharvest quality of peaches

“Hujin” and “Baihua” peaches (Prunus persica (L.) Batsch.) were treated at temperatures ranging from 37 to 43 °C for 1–3 h with hot water and for 3–48 h with hot moist air, respectively. Heat treatment with hot water caused heat injury to Hujin peach, and therefore is not suitable for Hujin peach.Hujin peaches were heated by moist air at 37 °C for 3–48 h. Heating of Hujin peach at 37 °C for 12 h was most effective in maintaining hardness and reducing mass loss, while for Baihua peach, the most effective treatment was heating at 37 °C for 16 h.

EFFECT OF MOIST HOT AIR TREATMENT ON SOME POSTHARVEST QUALITY ATTRIBUTES OF STRAWBERRIES

‘Northeaster’ strawberries were heated with moist hot air at 36, 39, 42, 45, 50 and 55C for 0, 20,40, 60, 80 or 100 min. Fruit were injured when exposed to temperatures 50C or higher, or durations of 60 min or longer at 45C. Treatment at 45C for 40 min or at 42C for 60–100 min resulted in the least decay incidence after 5 days at 0C, 3 days at 10C, and 1 day at 20C. Heated strawberries in general had lower titratable acidity, higher soluble solids content and higher levels of fructose, glucose, and sucrose than nonheated samples. Heated fruit also had a higher soluble solids/acid ratio, but lower citric acid and malic acid content. The lightness measurements, L*, and chroma values, C*, were decreased by moist hot air treatment and the fruit were duller and less bright in appearance after heat treatment. Strawberries heated at 39C or lower temperatures had no discernable differences from nontreated fruit in quality attributes measured. However, fruit treated with 45C for 40 min or 42C for 60–100 min maintained better postharvest quality than other treatments.

DRYING RATE AND TEMPERATURE PROFILE FOR SUPERHEATED STEAM VACUUM DRYING AND MOIST AIR DRYING OF SOFTWOOD LUMBER

Two charges of green radiata pine sapwood lumber were dried, either using superheated steam under vacuum (90°C, 0.2 bar abs.) or conventionally using hot moist air (90/60°C). Due to low density of the drying medium under vacuum, the circulation velocity used was 10 m/s for superheated steam drying and 5.0 m/s for moist air drying, and in both cases, the flow was unidirectional. In drying, stack drying rate and wood temperatures were measured to examine the differences between the superheated steam drying and drying using hot moist air. The experimental results have shown that the stack edge board in superheated steam drying dried faster than in the hot moist air drying. Once again due to the low density of the steam under vacuum, a prolonged maximum temperature drop across load (TDAL) was observed in the superheated steam drying, however, the whole stack dried slower and the final moisture content distribution was more variable than for conventional hot moist air drying. Wood temperatures in superheated steam drying were lower.

A Mold by Any Other Name

The Rare Book Room in Newman Library at Virginia Polytechnic Institute and State University was besieged with a mold bloom in August 1995. The causes were an unmonitored rise in heat and humidity from an air cooling system that continuously circulated hot moist air in from the outside, accumulated dust on the books, and an influx of unprocessed and unclean materials into the room. Cleanup involved placing books in an environment that would facilitate drying the mold, removing dry mold from books, and checking frequently for regrowth.

Exergy efficiency of a counterflow air/air heat exchanger with vapour condensation

The exergy efficiency of a counterflow hot moist air/ambient air heat exchanger with vapour condensation as a function of the temperature and humidity of the hot moist air, the ratio of ambient air flow rate to hot moist air flow rate and the minimum temperature differences between the flows is determined. The ranges 20 to 120°C and 0.01 to 1.0 kg·kg−1 for the temperature and humidity ratio of hot moist air respectively are considered. Constant ambient air conditions of 20°C and 0.01 kg·kg−1 were assumed.

Space-charge-limited-current diode model for CuxS/CdS solar cells and their degradation

A space-charge-limited-current diode model for CuxS/CdS solar cells accurately models their current-density-versus-voltage (J-V) curves for a 9.2% efficient device and a 4.1% efficient device that degraded to 0.3% efficiency in hot-moist air. For a 1-μm-thick, high-resistance region of Cu compensated CdS at the interface to the CuxS, all the measured fill factors from 0.54 to 0.71 and the open-circuit voltages from 0.41 to 0.52 V are well fit for steady-state conduction electron concentrations between 1.2×109 and 6.9×1010 cm−3 and for electron trap densities between 7×1014 and 5×1018 cm−3 eV−1 at energies of 0.3–0.5 eV below the conduction-band edge of this high-resistance CdS region. The trap changes that occur with short-circuit current degradation increase the fill factor. A CuxS/CdS configuration is proposed to reduce reproducibility problems and to eliminate all the known modes of degradation with the possible exception of photoinduced degradation. Efficiency increases of 10%–11% are projected.

Effects of Temperature and Humidity of Inhaled Air on the Concentration of Ethanol in a Man's Exhaled Breath

1. Ten healthy men each drank a moderate dose of ethanol in experiments to test if the temperature and moisture content of inhaled air could alter the concentration of ethanol in exhaled breath. 2. They breathed air at various temperatures and relative humidities (RH) for about 1 min before the concentration of ethanol and the temperature of end-expired breath were determined. Control breaths were analysed after the same men breathed ordinary room air (23°C, 55% RH). All tests were made during the postabsorptive phase of ethanol metabolism and the breath samples were analysed by gas-liquid chromatography. 3. When the men breathed cold dry air (5°C, 0% RH), the expired ethanol concentration decreased by 9·6 ± 0·69% (mean ± se) and breath temperature dropped by 1·40 ± 0·08°C. Cold moist air (5°C, 100% RH) decreased breath ethanol concentration by 6·4 ± 1·02% and breath temperature dropped by 1·1 ± 0·07°C. With hot dry air (80°C, 0% RH) as the breathing medium the concentration of ethanol was lowered by 4·3 ± 1·27% but expired breath temperatures were unchanged from the control tests. On breathing hot moist air (50°C, 100% RH), breath ethanol concentrations decreased by 10·3 ± 0·59%, even though breath temperatures rose by 1·8 ± 0·14°C above that of the controls. 4. Ethanol dissolves in the watery mucous membrane of the upper respiratory tract and can equilibrate with inhaled and exhaled air. It seems likely that during exchanges of heat and water vapour between respired air and the mucus, which largely depends on the temperature and humidity of inhaled air, the equilibrium of ethanol at the breath/mucus interface becomes disrupted. This leads to changes in the concentration of ethanol in expired air.