Quantification of the flow noise in household refrigerators

The flow noise in household refrigerators is quantified in this study. First, the sound pressure measurements in a quiet room using typical household refrigerators are conducted and the noise characteristics of the refrigerators are presented. Then, the flow noise in household refrigerators is quantified using the results of the overall analysis and Fourier transform of the measured sound pressure data. After that, the flow noise in household refrigerators is quantified using the sound pressure measurements conducted using a specially designed test rig. The frequency characteristics of the flow noise in household refrigerators are also explored and the contribution of the flow noise is identified

Hydrology and hydrochemistry of marble aquifer with point recharge from two deep sinkholes, Menderes Massive, western Turkey

Menderes Massive is a NE–SW-trending metamorphic terrain in western Anatolia. The massive is composed of regionally metamorphosed rocks of mica-schist and marble. The Bozdag Mountain is the main horst system in Kucuk Menderes river basin. It is composed of several N-S oriented small horsts and grabens and contains important karst features, such as poljes and sinkholes. Ayvacik and Subatan Poljes are typical closed depressions draining into Ayvacik and Subatan sinkholes (ponors). Both are developed along the N-S directed fault system. The main objective of this study is to determine the karstification and hydrogeochemical features of water circulating in marble terrain and controlled by deep sinkholes in the Bozdag Mountain. Detailed speleological studies demonstrated that the degree of karstification of marble rock depends on the regional tectonic structure, the mineralogy of marble and the water recharge rate into the sinkholes. Tritium isotope and tracer tests indicate very fast flow and connection between Subatan surface water and a spring in lower elevations with high Ca and Mg ion concentration at the south of the study area. Hidrogeologija in hidrokemija marmornega vodonosnika s ponornim točkovnim napajanjem (Masiv Meredes, zahodna Turčija)Masiv Menderes je območje metamorfnih kamnin v zahodni Anatoliji, Turčija. Razteza se v smeri SV–JZ in je sestavljeno predvsem iz regionalno metamorfiziranih sljudnih skrilavcev in marmorjev. Goro Bozdag sestavlja sistem manjših grud in tektonskih jarkov, orientiranih v smeri sever-jug. Masiv je delno zakrasel, s tipičnimi kraškimi oblikami, med katere spadata tudi polji Ayvacik in Subatan, ki se drenirata skozi istoimenske ponore. Obe polji sta razviti v prelomni coni orientirani v smeri sever-jug. Glavni namen opisane raziskave je določiti stopnjo zakraselosti območja in hidrokemične lastnosti vode, ki teče skozi marmornati masiv. Podrobne speleološke raziskave so pokazale, da je zakraselost močno pogojena z regionalno geološko strukturo, mineraloško sestavo marmorja in velikostjo dotokov v ponore. Izotopske analize tritija in sledenje podzemnih voda kažejo na hiter tok in povezavo med poljem Subatan in visoko mineraliziranimi izviri na jugu obravnavanega območja. 

Reaction kinetics of coal oxidation at low temperatures

Adiabatic oven testing of coal to assess the propensity for self-heating produces data on the kinetics of the coal oxidation reaction. Repeat tests on the same coal at different starting temperatures ranging from 20 to 57 °C shows that there is a strong time–temperature effect on the reaction kinetics. At these low temperatures the initial reaction rate is predominantly non-Arrhenius, but converges to Arrhenius behaviour at temperatures above 70 °C. A new rate equation model has been derived that accounts for the change in kinetic behaviour in the low temperature region. This model is based on the concept of reactive site availability

Effect of mineral matter on coal self-heating rate

Adiabatic self-heating tests have been conducted on subbituminous coal cores from the same seam profile, which cover a mineral matter content range of 11.2-71.1%. In all cases the heat release rate does not conform to an Arrhenius kinetic model, but can best be described by a third order polynomial. Assessment of the theoretical heat sink effect of the mineral matter in each of the tests reveals that the coal is less reactive than predicted using a simple energy conservation equation. There is an additional effect of the mineral matter in these cases that cannot be explained by heat sink alone. The disseminated mineral matter in the coal is therefore inhibiting the oxidation reaction due to physicochemical effects