This paper makes researches on a solar heating system with seasonal water tank heat storage(SHS-SWTHS) for a 9000m2 building located at Beijing,based on a similarity principle research method proposed by the present *...
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ISBN:
(纸本)9781479933372
This paper makes researches on a solar heating system with seasonal water tank heat storage(SHS-SWTHS) for a 9000m2 building located at Beijing,based on a similarity principle research method proposed by the present *** to the numerical results,the influence of the embedded depth of water tank on the system performance is analyzed based on two typical soils:granite and *** the granite soil,due to its high thermal conductivity and its high heat capacity,the system performance is affected greatly by the embedded *** the sand soil,due to its low thermal conductivity and its low heat capacity,the system performance nearly isn't affected by the embedded ***,with the increase of the embedded depth of water tank,the system performance tends to be consistent in different soils.
An investigation was conducted of the flow distribution characteristics of distribution header water-wall tubes under a supercritical pressure for a home-made 600 MW once-through boiler. The test parameters can be lis...
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An investigation was conducted of the flow distribution characteristics of distribution header water-wall tubes under a supercritical pressure for a home-made 600 MW once-through boiler. The test parameters can be listed as follows: pressure p=23-25 MPa, mass flow rate G=400-1200 kg/(m2·s), working medium temperature t=10-400°C. An experimental study has been conducted of the impact of working medium pressure, mass flow rate and working medium temperature on the vertical water-wall tube flow distribution characteristics of the distribution header. The test results show that with an increase in mass flow rate, the uniformity of flow distribution among the vertical water-wall tubes could be enhanced. The non-uniformity of flow distribution will undergo a step increase near the quasi-critical points. Moreover, with an increasing pressure, the above-mentioned step increase will become weaker. By employing a discrete model of the parallel-connected branch tubes of the distribution header, the flow distribution among the distribution header vertical water-wall tubes was calculated and the calculation results are in good agreement with the test ones.
In this paper, a new numerical procedure is proposed for the steady flow of a viscous, incompressible fluid based on SIMPLER algorithm on a non-orthogonal non-staggered grid, together with Cartesian velocity component...
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In this paper, a new numerical procedure is proposed for the steady flow of a viscous, incompressible fluid based on SIMPLER algorithm on a non-orthogonal non-staggered grid, together with Cartesian velocity components as dependent variables in the momentum equations. The main feature of the algorithm is that the pressure and pressure correction equations are obtained by explicitly treating pressure cross-derivatives terms in interface contravariant velocities. A collocated arrangement of variables is introduced on numerical grids, and the cell face velocities are calculated by the momentum interpolation. It is proved that this algorithm can be effectively used to simulate fluid flow and heat transfer in complex geometry, by the validation calculation of flow inside branching channel.
In this paper, a similarity principle research method is proposed to research the solar heating system with seasonal water tank heat storage (SHS-SWTHS). In this method, the similarity principle is applied to build a ...
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In this paper, a similarity principle research method is proposed to research the solar heating system with seasonal water tank heat storage (SHS-SWTHS). In this method, the similarity principle is applied to build a model. The time period of the model is one hundredth of the prototype, and the volume of the model is one thousandth of the prototype. Then, the numerical and experimental researches on the SHS-SWTHS system can be implemented based on this model, which has the following advantages compared with the prototype: (1) the computation time can be shortened largely, (2) the investment and experiment period can be decreased greatly. In this paper the feasibility of this model is verified by the numerical researches, in which the PISO algorithm is adopted to compute the fluid flow and heat transfer in the water tank and the coupled heat transfer between the water tank and the surrounding soil. The result will lay a foundation for the further numerical and experimental researches based on the model.
The maldistribution of two-phaseflow is one of the major factors that deteriorate the heat transfer performance of plate-fin heat exchanger. The set-up of flow distributor at the heat exchanger inlet is one widely ad...
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By adopting Level Set method and a Navier-Stokes equation coupled with a surface tension model and in combination with ALE (Arbitrary Lagrangian Eulerian) numerical algorithm, a direct numerical simulation was conduct...
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By adopting Level Set method and a Navier-Stokes equation coupled with a surface tension model and in combination with ALE (Arbitrary Lagrangian Eulerian) numerical algorithm, a direct numerical simulation was conducted of the rising process of two neighboring air bubbles inside a vertical channel. The emphasis was put on the study of the effect of 8 mm diameter air bubbles arranged at different spatial positions on the rear wake flows and their interactions. The numerical simulation can accurately reproduce the deformation, attraction and repellent action of the air bubble pairs. The calculation results of air bubble rising speed are in good agreement with those obtained by using an empirical formula. The simulation results show that the wake flows after the two air bubbles and their interaction determine the behavior of the rising air bubble pair. An air bubble pair rising side by side does not coalesce due to their wake zones being separated by a jet flow. When the air bubbles following the vertically rising air bubble pair have over 50% of their projection area entering the wake zones of their ahead air bubbles, however, a coalescence phenomenon will occur.
Hydrogen (H 2 ) is a clean and environmentally friendly energy carrier. The depletion of fossil fuels makes renewable H 2 production highly desirable. Water reforming of renewable biomass to hydrogen, with a relay of ...
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Hydrogen (H 2 ) is a clean and environmentally friendly energy carrier. The depletion of fossil fuels makes renewable H 2 production highly desirable. Water reforming of renewable biomass to hydrogen, with a relay of natural photosynthesis to biomass, would be an indirect pathway to realize the ideal but extremely challenging photocatalytic overall water splitting to hydrogen, with favorable thermodynamics. Since the seminal work of water reforming of biomass in 1980, great endeavors have been made. Nevertheless, hitherto, the entire kinetic pathway has been elusive, which seriously limits the reforming processes. Using a designed well-organized redox-neutral cleavage of C−C, O−H and C−H bonds enabled by photoelectrocatalysis, here, we show the efficient water reforming of biomass to hydrogen at room temperature, with a yield up to 93 %. The clear insights into the kinetic pathway with oxidation of carbon radicals to carbon cations as the indicated rate-determining step, would cast brightness for efficient and sustainable hydrogen production to accelerate the hydrogen economy.
The experiment on the non-catalytic steam gasification of bio-oil was carried out in a lab-scale fixed bed reactor. The influence of operating parameters such as the temperature and the mol ratio of steam to carbon (S...
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The experiment on the non-catalytic steam gasification of bio-oil was carried out in a lab-scale fixed bed reactor. The influence of operating parameters such as the temperature and the mol ratio of steam to carbon (S/C) on the gas yield and composition was investigated. The results show that increasing temperature can enhance the conversion of bio-oil to syngas;the carbon conversion of bio-oil can be as high as 97.8% at 1200°C, and the proportion of effective gas component (H2+CO) in the product gas is nearly 77% with a mol ratio of H2/CO=1.19. The mol ratio of H2/CO increases with an increase of S/C mol ratio, and reaches up to 3.69 at S/C=4. However, the addition of steam does not favor the increase of the composition of effective syngas. The product gas from steam gasification has a medium heating value.
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