Inside Temperature Profiles Research Articles

Hydrogen Production From Petroleum Hydrocarbons

Abstract The authors develop a small and simple steam-reforming reactor in a home-use size for such various heavy-hydrocarbons fuels as n-octane, n-decane, n-tetradecane, and n-hexadecane in addition to n-dodecane and measure the inside-temperature profile and the molar fractions of main-gas components such as H2, CH4, CO, and CO2. This reactor is designed only for laboratory-test use, not for a commercial product. As a result, the authors successfully achieve suitable inside-temperature profiles, namely, temperature almost linearly increases in the downstream direction along a reactor, under two conditions such as 600–950 K at the upstream end of the catalyst-layer bed in the reactor and less than 1070 K everywhere in the reactor. And, the authors reveal the effects of the liquid-hourly space velocity (LHSV) upon the molar fractions, a conversion ratio and reforming efficiencies for various heavy-hydrocarbons fuels. All the molar fractions, which agree well with thermochemical-equilibrium theory, are approximately independent of LHSV. The conversion ratio is about 90% for LHSV ≤ 0.6 h−1 and monotonically decreases with increasing LHSV for LHSV > 0.6 h−1. Then, each reforming efficiency always attains the maximum for LHSV ≈ 0.6 h−1 being independent of fuels. This suggests the common upper limit of LHSV for practically suitable operation.

Air infiltration assessment for industrial buildings

This work focuses on air-tightness and air-infiltration of industrial buildings of light steel structure. Extensive measurements of leakages in typical building components and connections in industrial buildings were carried out in a specially built air-tightness test stand. Typical leakages were detected and reduced. Measurements of the volumetric flow through single leakages were compared to results of blower door tests of large industrial buildings. The measurement data gained in the test stand was further used for transient air-flow network simulations coupled with the software TRNSYS. Based on a database of more than 4000 industrial buildings, 28 typical building shapes were defined and different inside temperature profiles were assumed. Each building was modeled and simulated with up to 84 defined cracks. The cracks were based on the measurements in the test stand and represent a typical leakage distribution of industrial steel buildings. In total 140 different simulations were used to create a new infiltration model. This model provides monthly coefficients that consider the seasonal cycle during the year as well as the building height, size and inside temperature. This new model is easy to implement in energy balance calculations and helps determining energy demands even with steady state methods with greater precision.

Steam regeneration of acetone and toluene in activated carbon and dealuminated Y-zeolite beds

The dynamics of steam regeneration in activated carbon and dealuminated Y-zeolite (DAY-zeolite) beds was studied to recover acetone and toluene from effluent gases. Due to the higher adsorption capacity of acetone on both adsorbents, the desorption breakthrough of toluene was faster than that of acetone, but the breakthrough shape of acetone was steeper than that of toluene. The variation in breakthrough time as a function of steam flow rate was less in the activated carbon bed than in the DAY-zeolite bed. The inside temperature profiles during regeneration showed stepwise shapes. A temperature plateau was observed near 355 K for toluene, which is lower than its boiling temperature and azeotrope. A temperature plateau for acetone occurred near 330 K, near its boiling temperature. The duration of the temperature plateau at the bed end corresponded with the time period of high desorption concentration during acetone desorption; for toluene, plateau duration was shorter than the duration of high desorption concentration. The maximum effluent concentration of toluene reached only 80% of the feed concentration, while that of acetone was almost 100%. Therefore, the water-miscibility of the adsorbate was an important factor in steam regeneration.

C104 様々なLHSVでの高次炭化水素燃料の水蒸気改質における反応温度の影響について(OS5 水素・燃料電池)

The authors develop a small and simple steam-reforming reactor in a home-use size for n-dodecane as a heavy-hydrocarbons fuel. Under the thermal condition controlled by electric heaters and a gas burner with a thermal diffuser, the authors measure the inside-temperature profile and the hydrogen molar fraction (concentration) C_<H2>, together with the molar fractions C_<CH4>, C_<CO> and C_<CO2> of other main gas components such as CH_4, CO and CO_2, respectively. As a result, the authors successfully achieve suitable inside-temperature profiles. And, the effects of the liquid-hourly space velocity LHSV upon the molar fractions and a conversion ratio X_<C12H26>, experimentally. Furthermore, the authors reveal the effects of the temperature T inside the reactor upon them molar fractions, comparing with the thermal-equilibrium theory in a wide range of LHSV.

The Effects of LHSV and Reaction Temperature upon Steam Reforming for Heavy Hydrocarbons

The authors develop a small and simple steam-reforming reactor in a home-use size for n-dodecane as a heavy-hydrocarbons fuel. Under the thermal condition controlled by electric heaters and a gas burner with a thermal diffuser, the authors measure the inside-temperature profile and the hydrogen-molecule ratio (concentration) RH2, together with the molecule ratios RCH4, RCO and RCO2 of other main gas components such as CH4, CO and CO2, respectively. As a result, the authors successfully achieve suitable inside-temperature profiles. And, the effects of the liquid-hourly space velocity LHSV and of the temperature T inside the reactor upon the molecule ratios are revealed, as well as the LHSV effect upon the conversion ratio. The comparison with the thermal-equilibrium theory indicates that the temperature at the catalyst-layer-bed downstream end could be regarded as the reaction temperature.

Hydrogen Production by a Reactor for Heavy Hydrocarbons

The authors develop a small and simple steam-reforming reactor in a home-use size for n-dodecane as a heavy-hydrocarbons fuel. Under such a well-controlled condition by a thermal diffuser as the reactor satisfies two target-temperature criteria, the authors measure the inside-temperature profile and the hydrogen-molecule ratio (concentration) RH2, together with the molecule ratios RCH4, RCO and RCO2 of other main gass components such as CH4, CO and CO2, respectively. In addition, the authors conduct theoretical calculations, as well as experiments. As a result, the authors successfully achieve suitable inside-temperature profiles. The effects of the steam-to-carbon molar ratio S/C upon RH2, RCH4, RCO and RCO2 are shown, experimentally and theoretically. The experimental results agree well with the theoretical ones. Besides, both carbon balance and conversion ratio show high accuracy in experiments.

D213 高次炭化水素燃料を用いた水蒸気改質器による水素製造(OS4 水素・燃料電池),動力エネルギーシステム部門20周年,次の20年への新展開)

The authors develop a small and simple steam-reforming reactor in a home-use size for n-dodecane as a heavy-hydrocarbons fuel. Under such a well-controlled condition by a thermal diffuser as the reactor satisfies two target-temperature criteria, the authors measure the inside-temperature profile and the hydrogen-molecule ratio (concentration) R_<H2>, together with the molecule ratios R_<CH4>, R_<CO> and R_<CO2> of other main gass components such as CH_4, CO and CO_2, respectively. In addition, the authors conduct numerical simulations, as well as experiments. As a result, the authors successfully achieve suitable inside-temperature profiles. The effects of the steam-to-carbon molar ratio S/C upon R_<H2>, R_<CH4>, R_<CO> and R_<CO2> are shown, experimentally and theoretically. The experimental results agree well with the theoretical ones. Besides, both carbon balance and conversion ratio show high accuracy in experiments.

F201 燃料電池向けn-ドデカン水蒸気改質の基礎研究(OS5 水素・燃料電池)

We has developed a small and simple steam-reforming reactor in a home-use size for n-dodecane as a heavy-hydrocarbons fuel. The reactor satisfy the target thermal conditions by the control of a thermal diffuser. Under the conditions, we measure the inside-temperature profile, and the hydrogen-molecule ratio R_<H2> together with the molecule ratios R_<CO2>, R_<CO> and R_<CH4> of other main gass components such as CO_2 CO and CH_4, respectively, using a gas chromatography. The effects of steam-to-carbon ratio S/C upon R_<H2>, R_<CO2>, R_<CO> and R_<CH4> are shown, experimentally and theoretically. The experimental results agree with the theoretical ones qualitatively, but not qualitatively especially for R_<H2> and R_<CH4>.

Electrochemical experimental method for natural convective heat and mass transfer in porous media

Natural convection driven by combined thermal and solutal buoyant forces in a fluid-saturated porous enclosure was studied experimentally. An electrochemical method was employed to establish the concentration gradients. The inside temperature profiles and heat and mass transfer coefficients on the vertical walls were determined experimentally. The effects of dimensionless parameter Ra, Le, N on flow, heat, and mass transfer are discussed in detail.