Global NEST Journal

The present study is performed with the aim to reduce the levels of polluting emissions from fuel combustion that produce acid rains and the greenhouse effect (NOx, CO2). The electric field effects on the processes of heat/mass transfer and propane combustion are studied in order to perform electric control of the levels of polluting emissions from the flame. The results of experimental studies show the direct influence of the electric field's enhanced mass transfer on local variations of the flame composition and fuel combustion. The related variations of the flame temperature, processes of soot formation, carbon capture and deposition along the flame channel flow are studied by varying the field strength and the equivalence ratio of the propane-air mixture. The results show that the electric field effect on soot for- mation, carbon capture and sequestration, for fuel-rich flame flow, can be used to reduce the levels of CO2 emissions from the flame. In addition, the field-enhanced heat/ mass transfer to the channel walls, for fuel-lean conditions, can be used to control the fuel combustion, flame temperature and temperature- sensitive levels of NOx emissions. The most pronounced electric field effects on fuel combustion and composition of the products are observed in the limit of the weak fields (U<1,2 kV, E<105 V m-1).

The malaria situation in Bulgaria during the past decade of the century was analysed and the evaluation
of the risk of re-emerging of the diseases and factors determining it in the phase of maintanence
of malaria eradication was carried out. The epidemiological analysis of malaria cases notified during
the period 1991-2000 in Bulgaria is presented. Of a total of 382 malaria episodes registered, 363
(95.03%), were imported into Bulgaria from endemic countries, 1 (0.26%) occurred after haemotransfusion
and 18 (4.71%) were indigenous introduced ones. Plasmodium falciparum accounted for 68.59%
of all imported cases, P.vivax, for 23.82%, P.ovale, for 2.36%, P.malariae, for 1.85%. In 1.83% more
than one species was detected, and in 6 cases, the species was not identified. The import of malaria
came mainly from Africa-299 (82.37%) cases, followed by Asia-63 (17.36%) and Oceania-1 (0.27%).
Four cases with falciparum malaria resulted in death. A great number of imported cases-231 (63.81%)
was diagnosed during the potential malaria season in Bulgaria (April-October). The analysis of present
entomological situation showed a high density of Anopheles population. As an indication for existence
of potential risk of spread of indigenous malaria, especially in cases of delayed diagnosis and treatment,
18 indigenous cases of vivax malaria were recorded in 1995-1996 in the region of the town of Sandanski,
for the first time after malaria eradication in 1965. The cases were classified as introduced ones. The
analysis of the essential malaria import in Bulgaria, climatic conditions and presence of Anopheline
species revealed a fairly high level of malariogenic potential. The stratification of the country was carried
out in accordance with the degree of hazard of malaria spreading, and the territory was divided
into three categories of regions: with high-, medium- and low-risk. The present situation, that probably
will be valid for the future, too, requires a scientific based prognosis and improvement of a system of
surveillance activities aiming at prevention of indigenous endemic and epidemic spreading of malaria
in the country, as well as elaboration of adequate activities of the health network in case of reappearance
of autochthonous cases.

Air pollution is changing the ecosystems, especially in Europe. Tropospheric ozone may adversely
affect tree growth, with critical levels for ozone being exceeded in many parts of Europe, especially in
the Czech Republic. This research reports the information on exceedances of ozone threshold values
for the period 1994 to 2000 and gives an evaluation of the observed exceedances of the thresholds during
the vegetation period (April-September) and from May to July at the Bílý Køíž station. The threshold
for warning of the public (240 ìg m-3 as hourly average concentration) was not exceeded at the Bílý
Køíž station for the studied period. The threshold value for information to the population (180 ìg m-3
as hourly average concentration) was exceeded in 1994 (July and August), 1995 (May and July), 1998
(August) and 2000 (June). The threshold value set for the protection of human health population (120
ìg m-3 as eight-hourly average concentration) was exceeded for all period at the Bílý Køíž station.

Electricity generation in solid fuel fired power stations is currently the main source of flying particulates
and greenhouse gases emissions. Environmental pollution is expected to deteriorate dramatically
in the coming century unless pollution abatement technologies for solid fuels energy conversion will be
applied. The Integrated Gasification Combined Cycle (IGCC) system, currently under industrial testing,
provides for high solid fuel energy conversion efficiency (e.g. ~ 45 %) and favors the application of
proven technologies for gas purification (e.g. H2S oxidation to elemental sulfur, CO2 separation and
disposal as a stable carbonate solid). Additionally, gasification combined with fuel cell technology
(CGFC) may provide in the long run, for energy conversion efficiency well over 50%. This article
reports also the results of pilot plant lignite gasification tests for the production of a medium heating
value synthesis gas using a novel indirect heat (allothermal) gasification process (ALLOGAS). The latter
process employs an indirect heat rotary kiln gasifier and is considered as the most appropriate to
gasify moist lignite with the minimum pretreatment.