Dry Burning Research Articles

Heat transfer properties and chaotic analysis of parallel type pulsating heat pipe

The refrigerant mixture of ethanol aqueous was applied to the parallel type pulsating heat pipe (PHP). The operation characteristics of the PHP were analyzed by means of experiment and nonlinear chaotic theory. Moreover, the relationship between the running state and attractor was described. The results indicate that starting power, stable running power and dry burning transition power are about 64.08 W, 148.68 W and 234.0 W respectively. The cycle and amplitude of PHP initially decrease and then increase with the increasing power. However, the data are well-distributed in a certain range. The running state is in agreement with the attractors, and the changing process for attractors is as follows: the attractors first disperse in the whole phase space, then present mass status, and finally show band distribution.

Seasonal variation of ozone deposition to a tropical rain forest in southwest Amazonia

Abstract. Within the project EUropean Studies on Trace gases and Atmospheric CHemistry as a contribution to Large-scale Biosphere-atmosphere experiment in Amazonia (LBA-EUSTACH), we performed tower-based eddy covariance measurements of O3 flux above an Amazonian primary rain forest at the end of the wet and dry season. Ozone deposition revealed distinct seasonal differences in the magnitude and diel variation. In the wet season, the rain forest was an effective O3 sink with a mean daytime (midday) maximum deposition velocity of 2.3 cm s−1, and a corresponding O3 flux of −11 nmol m−2 s−1. At the end of the dry season, the ozone mixing ratio was about four times higher (up to maximum values of 80 ppb) than in the wet season, as a consequence of strong regional biomass burning activity. However, the typical maximum daytime deposition flux was very similar to the wet season. This results from a strong limitation of daytime O3 deposition due to reduced plant stomatal aperture as a response to large values of the specific humidity deficit. As a result, the average midday deposition velocity in the dry burning season was only 0.5 cm s−1. The large diel ozone variation caused large canopy storage effects that masked the true diel variation of ozone deposition mechanisms in the measured eddy covariance flux, and for which corrections had to be made. In general, stomatal aperture was sufficient to explain the largest part of daytime ozone deposition. However, during nighttime, chemical reaction with nitrogen monoxide (NO) was found to contribute substantially to the O3 sink in the rain forest canopy. Further contributions were from non-stomatal plant uptake and other processes that could not be clearly identified. Measurements, made simultaneously on a 22 years old cattle pasture enabled the spatially and temporally direct comparison of O3 dry deposition values from this site with typical vegetation cover of deforested land in southwest Amazonia to the results from the primary rain forest. The mean ozone deposition to the pasture was found to be systematically lower than that to the forest by 30% in the wet and 18% in the dry season.

Avaliação da queima e da adição de milho desintegrado com palha e sabugo na ensilagem de cana-de-açúcar

Neste trabalho, avaliou-se a fermentação da cana-de-açúcar queimada, ensilada com ou sem uso de aditivo seco. Os tratamentos (seis no total) consistiram da silagem de cana crua ou queimada, adicionada de 0, 50 ou 100 g/kg de milho desintegrado com palha e sabugo (MDPS), com base no peso verde da forragem. Foram determinados os teores de MS, PB, nitrogênio insolúvel em detergente ácido (NIDA), FDN, FDA, celulose, hemicelulose e lignina. Na avaliação das características fermentativas, foram determinados os valores de carboidratos solúveis, o poder tamponante, o pH e as concentrações de nitrogênio amoniacal e etanol. Como características microbiológicas, avaliou-se o desenvolvimento de leveduras. A inclusão de MDPS elevou os teores de MS e reduziu discretamente os teores de N-NH3 e etanol das silagens, não ocasionando efeito nos valores de pH e na população de leveduras. A presença do fogo reduziu a concentração de MS das silagens, elevou os teores de etanol e leveduras e diminuiu os teores de N-NH3. A fermentação etanólica durante a ensilagem não foi controlada com a inclusão de aditivo seco ou com o uso do fogo.

Changes in Reproductive Habitat of Gray Partridge after Burning

We investigated the effects of winter controlled burning on the breeding habitat of the Pyrenean gray partridge (Perdix perdix hispaniensis Reich.). Floristic composition and vegetation structure were sampled on 198 sites, including 64 recently used by hens for nesting or rearing of broods, 90 within partridge habitat burned under conditions, and 44 burned under conditions. During the early breeding season, birds selected shrublands of broom (Cytisus purgans (L.) Boiss.) with an average canopy coverage of 60% and an average height of 0.50 m. Birds avoided sites where shrub cover was more than 80% or less than 20%. The most critical effect of burning on gray partridge brood habitat was the reduction of the cover in the 2 vegetation layers providing protection against predators (0.05-0.25 m, and 0.25-0.50 m). In the case of dry burning, the recovery of suitable habitat took more than 8 years for nesting hens and flightless chicks, but only 5-6 years for broods older than 3 weeks. Data obtained by radio-tracking eight broods indicated that wet burns (mean size = 4 ha) were better than dry burns (mean size = 15 ha) for maintaining good brood habitat. For the dry burns, we recommend that burned patches be equal to or less than 5 ha and separated by unburned patches of 10-15 ha. In both cases, the frequency of fires should not exceed once every 15-20 years.

A Field Comparison of Wet and Dry Combustion

The injection of water during an in-situ combustion process has been shown with laboratory studies to be more efficient than dry combustion. This paper substantiates the superiority of wet combustion over dry burning with field data from the Bodcau in-situ combustion project in Bossier Parish, LA. Introduction Cities Service Co. operates an in-situ combustion project in the Bellevue field of Bossier Parish, LA (Fig. 1). The field was discovered in 1921 and covers approximately 900 acres (3.64 km2). Production is from the Upper Cretaceous Nacatoch sand occuring between 300 and 400 R (91 and 122 m). Porosity and permeability of the unconsolidated reservoir average 33.9% and 700 md, respectively. The 19 degrees API (931-kg/m3) gravity crude has a viscosity of 676 cp (0.68 Pas) at the reservoir temperature of 75 degrees F (24 degrees C). Due to the low reservoir pressure and high viscosity of the oil at reservoir temperature, typical producing rates are 1 or 2 BOPD (0.16 to 0.32 m3/d) per well. Reservoir properties are summarized in Table 1.Dry forward combustion was tested by Cities Service in a pilot started in 1971. Other production stimulation techniques had been tried in the field, but none were economically successful. Production from the four 2.5-acre (10 117-m2) inverted nine-spot patterns during the 3-year combustion phase was in excess of 167,000 bbl (26 550 m3). The pilot area is still under waterflood, and ultimate recovery will exceed 40% of the original oil in place. Although the pilot test demonstrated that dry combustion could recover the low-gravity crude economically, laboratory studies indicated that wet combustion would be superior to dry combustion in the Bellevue field. To compare the two combustion processes directly, a field test was begun in 1974.Successful results from the field test led to the development of eight additional patterns using wet combustion, including five operating under a contract with the U.S. DOE. The DOE project demonstrates the technical efficiency and economics of a commercial combustion project. Eight more patterns have been drilled and presently are being developed, while additional acreage is being prepared for future fireflooding operations (Fig. 2). Description of Test Area Two 2.5-acre (10 117-m2) inverted nine-spot patterns were developed as shown in Fig. 3. Pattern 6 was to be processed by dry combustion, while Pattern 5 would make use of a type of wet combustion specifically designed for this reservoir. To monitor the progress of the combustion and water fronts, 18 temperature observation wells were drilled within two patterns.Producing wells were completed with 7-in. casing cemented to surface. The entire pay interval was perforated at a density of two hots per foot, and the wells were equipped for beam pumping. Injection wells also were completed with 7-in. (18-cm) casing, but only the bottom 15 ft (4.6 m) of pay were perforated for air injection. JPT P. 1523^