The dependence of CH₄ gas production on digester temperatures and volatile solid (VS) loading rates was investigated. Erlenmeyer flasks with a 1×10^-3m³ capacity were used as digesters. Liquid fraction, after the solid-liquid separation of dairy cattle manure, were digested by semi continuous operation under the conditions of the temperatures of 20, 30, 35, 40 and 48°C, VS loading rates of 3.0, 6.6, 10.2, 14.8 and 21.9kg-VS·m^-3·day^-1, and manual shaking of flasks twice a day. CH₄ gas production rates were measured by using floating cap type gas holders. The results were as follows;
(a) The dairy cattle manure should be digested at a digester temperature of approximately 40°C.
(b) The liquid fraction was digested better with a higher VS loading rate contrary to conventional values.

View full abstract

Prediction of air flow pattern affected by incoming jet directions was performed in a confinement livestock house by using FEM assuming a two dimensional, steady state, isothermal, incompressible and viscous air flow. Zero equation model was applied as a turbulent model. The numerical analysis used in the study assumed the use of a microcomputer, and the results obtained from the numerical analysis were examined by comparing with those of the model experiment. The findings indicate that even if pens and sows existed as obstructions in ventilated space, and even when incoming jet direction differed, a rough agreement between FEM and model experiment was observed for qualitative air flow pattern. With regard to air velocity, such agreement was not obtained.

View full abstract

Effects of light quality of artificial light source on the growth and morphogenesis of tomato and kidney bean were studied. White, red, yellow, green and blue lamps were used as artificial lights in the experiment. The light quantum irradiated for plants was set up at 2 levels of 400 and 200μmol·m_-2·s_-1and 300 and 150μmol·m_-2·s_-1 in photosynthetic photon flux density (PPFD) for tomato and kidney bean, respectively. Plants were grown hydroponically in the growth cabinet in which air temperature was maintained at 20/19°C (day/night) and day length was regulated to 12hr. Treatments were conducted for 14 and 30 days for tomato and kidney bean, respectively.
1) When plants were grown under high light intensity, leaf burning was occurred under green and blue lamps 5 to 6 days after treatment. The symptom, however, was not recognized under low light intensity. The internode of tomato plants under white lamp was longer than that under others. Dry weights of tomato and kidney bean plants under green and blue lamps were 15 to 30% lower as compared with other treatments. As the light under green and blue lamps contained higher rate of ultra-violet, it was suggested that uv seemed to cause leaf injury and to succulent the growth.
2) When tomato plants were grown under high and low light intensity, partioning of dry matter to the stem was higher under white than red or yellow. On the contrary, the its partioning to lateral shoot was 5 to 10 times higher under red or yellow than that under white. From these results, it was suggested that red/farred ratio affected the partioining of dry matter to each organ.
From the results obtained, it is concluded that light quality was recognized as growth reduced the plant growth by high light intensity of green or blue. However, that effects was not recognized clearly under low light intensity. Dry matter partioning, plant morphology, etc, were seemed to be affected with light quality regardless of light intensity.

View full abstract

Experiments were performed on a packed bed of large diameter, based on the previous experimental results of packed bed of small diameter. Aeration rates were selected systematically while the other experimental conditions were kept as similar as possible to those of the previous study. Radial temperature distribution effected by the wall, and the quantity of radial heat transferred were investigated. It is clear that the maximum temperature rose as the diameter of packed bed was increased, and the transition of distribution of temperature was very complex. By comparing the heat conduction in regions bounded by the surface of the cylindrical co-ordinate system, classified by aeration rates, the fairly complicated heat transfer phenomena involving exothermic and endothermic reactions of the materials of packed bed, were elucidated. By measuring the temperature at mid-area center of each layer, and simplifying the thermal engineering calculations involved, it was possible to estimate the distribution of temperature in the packed bed.

View full abstract

Using synthetic wastewater and swine waste, a bench scale of fluidized bed methane fermentor was operated to elucidate its characteristics and probabilities for the treatment of wastewaters. The following results were obtained:
1) We have established the excellent startup of the reactor within 3 to 7 days using seeding sludge followed by separation of solids by sieve (2.0mm opening) under anaerobic condition (N₂ purge).
2) Using synthetic wastewater, it was shown that the concentration of methane microbes in fluidized bed fermentor was ca. 10 times higher than that of the conventional methane fermentor. It would suggest that 80% of the substrate removal was due to the high SRT (over 12 days) which was established by the maintenance of methane microbes in the fermentor.
3) During the preliminary experiments using the supernatant of swine wastewater, 72% of VS removal and 0.75m³/kg-VS of gas yield were obtained at the maximum Lvs of 6.46kg-VS/m³·d.
Based on the results mentioned above, it would suggest that this type of methane fermentor has higher probabilty for the application of treatment of wastewater containing organic matters with high concentration.

View full abstract

This study explains the environments of the low cost windowless swine building during summer. The structure had a curved roof. The framework was consisted of steel pipes, and the walls were made of reflective film to reduce the construction cost. The wall had the ventilation layer with double fixed coverings for decreasing the heat load caused from the outside during summer. The ventilation layer had a thickness of 0.2m. The ventilation system was a positive pressure ventilation. The ventilating fan on the gable flew the outside air into the room. The outside air was distributed equally in the longitudinal section of the room by using the ventilation duct. Three kinds of ducts which have one, two or four openings on the cross section were tested in this experiments. The internal curtain was tested to keep the air flow distribution in a good condition. The room air was exhausted to the outside through the ventilation layer. The results from measurements were as follows;
1. The room temperature was about 1.5K to 1.9K higher than the outside air temperature in the summer night time and was about 1K higher than the outside air temperature in the day time. As the room temperature was changed together with the outside air temperature, the room temperature might not be affected directly by the solar radiation.
2. From the relationship between the number of air changes and the inside-outside air temperature difference, it was clarified that the number of air changes in the room, which was more than or equal to about 20 times/h was required to keep the inside-outside air temperature difference within 1K during summer day time.
3. By using with the ventilation ducts having one opening on the cross section, we got the two patterns of air flow distribution in the room having internal curtain or no curtain. These patterns showed the better air flow distribution than the other patterns obtained by using the ventilation duct having two or four openings. Among these patterns, the best pattern was obtained at the time when the air flew along the internal curtains, because the air flew to the pigs directly.
The mathematical model of predicting the room temperature was based on the following assumptions. For the soil floor had the largest heat capacity in the construction materials of the room, the heat transfer of the soil was treated as the unsteady state in the mathematical model. As the heat capacities of steel pipes and film were small, the heat transfer of these materials were treated as the steady state. From the assumptions, it clarified the following.
4. The wall that had the ventilation layer consisted of the double fixed covering could make the room temperature about 2.0K lower in the summer day times and about 0.2K higher in night than the temperature of the case having the single fixed covering wall.
5. In the summer day time, the heat transfer through the wall having the ventilation layer consisted of the double fixed covering was about 35% of the heat transfer through the single fixed covering wall of windowless swine pipe building.

View full abstract

In the design stage of natural ventilation of greenhouse, wind pressure coefficient of opening is necessary. In this experiment, a model (1: 12) of one type of high tunnel greenhouse with side opening, ridge opening, and with entrance/exit at gable end was installed in a boundary layer wind tunnel to determine the wind pressure coefficient at the surface and for three opening conditions. The results obtained showed that wind pressure coefficient at the surface of high tunnel changed at various wind direction, such as at wind direction angles of 0°, 30°, 60° and 90° as illustrated in Fig. 4. The wind pressure coefficient of side opening, ridge opening, and entrance/exit at gable end at various wind direction as shown in Fig. 5 also indicated this trend. The wind pressure coefficients across the opening were different from those at the surface when the ventilators were closed, so that the calculation of ventilationrate should be based on the values at ventilators open.

View full abstract

In this study, particle movement and distribution of brown rice and rough rice on a shaking tray of a rice separator were investigated for analyzing the separating characteristics of the brown rice from the rough rice on a tray by oscillating separation. Over several mixing ratio of a rice mixture, experiments were carried out to clarify complicate phenomena on a tray and investigate necessary assumptions to develop a separating model, and the following findings were obtained: (1) Total zone of a rice mixture on a tray could be divided into an entrance zone, a separating zone and a conveying zone. The size of each zone was affected by a mixing ratio. (2) The brown rice movement in conveying direction could be assumed to be an apparent uniform flow, however, it could not be assumed for rough rice. The rough rice on a tray had larger moving velocity in that direction than the brown rice. (3) The distribution of a rice mixture in separating direction could be grasped using a mass centroid pathway, a standard deviation and a skewness degree.

View full abstract