Hiroshi Hayasaka

Peat-fire-related air pollution in Central Kalimantan, Indonesia

The past decade marked record high air pollution episodes in Indonesia. In this study, we specifically focus on vegetation fires in Palangkaraya located near a Mega Rice Project area in Indonesia. We analyzed various gaseous air pollution data such as particulate matter (PM10), SO2, CO, O3, and NO2 study region. We also conducted elemental analysis at two different sites. Results from 2001 to 2010 suggested the longest hazardous air pollution episode during 2002 lasting about 80 days from mid-August to late-October. Maximum peak concentrations of PM10, SO2, CO, and O3 were also observed during 2002 and their values reached 1905, 85.8, 38.3, and 1003×10(-6) gm(-3) respectively. Elemental analysis showed significant increase in concentrations during 2011 and 2010. Satellite retrieved fires and weather data could explain most of the temporal variations. Our results highlight peat fires as a major contributor of photochemical smog and air pollution in the region.

Estimation of Thermal Balance in Heptane Pool Fire

In order to predict the scale dependency of fire property in oil tank fires, we estimated the thermal balance of generated heat from the fire with a simple fire model, a so-called one mesh model. In this estimation, both ex perimental values of burning rate and air entrainment in heptane pool fires were used. For 1 m tank fires, it was found that about 70% of the generated heat was lost as upward convective heat and about 30% was lost as radiative heat, and only about 1% was used for fuel vaporization. The ratio of upward convec tive heat became larger with tank size. Experimental results show that the radiative fraction went down in fires larger than 1 m diameter because of the huge smoke emission.

Radiation measurements in large-scale kerosene pool flames using high-speed thermography

Details of apparent temperature distributions in large-scale kerosene pool flames in a 2.7 m square tank were measured by high-speed thermography which stores a thermal image in the form of a thermal TV color image with 25,600 data points every 0.1 second. The apparent temperature image can be changed to irradiance by simple approximations. The irradiance of the data (4 cases and 280 images) was compared with that of a wide-angle thermopile radiometer to verify the data from the thermography. A series of data recorded at intervals of one and five seconds was also analyzed to obtain the radiance distribution in the flame. The analysis allows the following conclusions: Irradiance values obtained by high-speed thermography are not very different from those of a conventional wide-angle thermopile radiometer. The high radiance zone, which ordinary cameras do not show, was determined by the average value of each of 70 apparent temperature images, and the center of the high radiance zone is located at about 0.3 D (D is the tank diameter). The moderately high apparent temperature range of 1232K–1448K apparently has a strong influence on the irradiance of pool flames.

Radiative characteristics and flame structure of small-pool flames

A new way of using thermography for radiative objects like pool flames has been developed by the author. The thermography method, which has already been applied to large pool fires, is applied to small pool flames in this paper. The radiative characteristics and flame structure of small pool flames are considered by examining flame temperature distribution from a radiation point of view. In addition, it is shown that pool flame structure for various fuels becomes clearer using the standard deviation and the coefficient of variation obtained from thermographic data.

Peat Fire Occurrence

In this chapter, various peat combustion properties, temporal and spatial peat fire occurrence in Kalimantan, and the peat fire index (PFI) for the early warning of peat fire were discussed. Firstly, tropical peat was sampled from Mega Rice Project (MRP) area in Central Kalimantan and analyzed in the laboratory. The flash point, ignition temperature and calorific value of tropical peat were measured by using a thermogravimetry and differential thermal analysis (TG-DTA) and a bomb calorimeter. The ignition probability of tropical peat was estimated by using literature values. In fields of the study area, peat ignition test, surface temperature measurement of actual burning peat and peat fire propagation measurement were carried out to identify actual peat fire conditions. Secondly, recent seasonal and special fire occurrence trends in Kalimantan were discussed using analysis results of MODIS hotspots data (fires) and precipitation data (the 10 years data, from 2002 to 2011). The two provinces of Central and West Kalimantan have the different severe fire periods. The fire season in West Kalimantan started in early August and lasted until early September. On the other hand, the fire season in Central Kalimantan started in middle August and continued until early November. Finally, peat fire index (PFI) derived from monthly and daily rainfall data was proposed to estimate peat fire conditions. The PFI has a linear relationship to the annual lowest groundwater level in peatland with the coefficient of determination R2 = 0.84, and to the total number of hotspots observed by MODIS during the dry season from June to November in Central Kalimantan with R2 = 0.74. The PFI was found to be useful for the early warning of peat fire in tropical peatlands. The depth of combustible peat layer increased linearly with lowering of groundwater level in tropical peatlands.

Backdraft Experiments in a Small Compartment

This paper describes results of preliminary backdraft experiments in a 0.85 m high, 0.78 m wide, 1.08 m long compartment, a roughly one third scale residential room. Each surface of the compartment was made with two layers of insulation board to obtain a highly insulated condition. The compartment had a small opening in the middle of the front wall to realize a low-ventilation condition. Interior wall surfaces including the ceiling were partially or fully covered with 12 mm thick wood to simulate a room fire. This wood was the fuel for the fire. A total of 17 experiments were carried out to find backdraft occurrence conditions for the low-ventilation, highly insulated compartment, and to understand backdraft phenomena.

Severe Air Pollution Due to Peat Fires During 2015 Super El Niño in Central Kalimantan, Indonesia

Severe air pollution due to biomass burning occurred again in Indonesia during the 2015 super El Nino. In this study, air pollution data measured at Palangkaraya, near the northern part of the Mega Rice Project (MRP) area in Kalimantan, are analyzed in conjunction with fire and precipitation data, and satellite imagery. During super (very strong) El Nino conditions in 2015, the dry season lasted about 150 days from late-May to late-October, with low precipitation (=1.0 mm day−1; average precipitation in dry season = 3.9 mm day−1). Forest and peat fires became active around mid-August, about 3 months after the onset of the dry season, followed by a period of severe air pollution (PM10 > 420 × 10−6 gm−3; Hazardous level) starting in mid-September and lasting through late-October. These time-lags between the dry season, fires, and air pollution period suggest that biomass fuel needs about 3 months to become dry enough to start active fires, and that peat underground needs about 4 months to become ignitable dry peat. After severe peat fires began in late-September, highest daily and hourly PM10 concentrations (3010 and 3760 × 10−6 gm−3, respectively) were observed on October 20, 2015. These fire and air pollution occurrence tendencies suggest that peat fires are the main source of air pollution.

Radiative Heat Transfer Analysis in a Marine Boiler Furnace

The improvement of marine boiler furnaces has mainly been done empirically because of complicated furnace phenomena such as combustion, heat transfer and flow. Among them, heat transfer by radiation is especially important because heat transfer to the furnace wall is mainly by radiation. New analytical methods are proposed for the radiative heat transfer analysis to increase the accuracy and to reduce the computation time as compared with the conventional Monte Carlo method.

Improvement in radiatine heat transfer analysis by the Monte Carlo method.

モンテカルロ法による放射熱伝達の解析手法は,ゾーンメリッドと比較して,解析適用上の制約が少なく三次元への拡張も容易である.この反面,解の精度の高い計算を行なうためには,乱数を多く使うことで,対処しており,このため,比較的長い計算時間が必要となるなどの短所もある.そこで,従来のモンテカルロ法の解析手法を再検討して,解の精度の高い,しかも計算時間の短い新しい解析手法を提案した.