Energy Conservation Characteristics Research Articles

Liquid flow glazing contributes to energy-efficient buildings: A review

This work gives a precise review of the researches completed on the energy conservation characteristics of liquid flow glazing. Its energy saving and environmental benefits under various design and operation conditions, contributions with renewable energy utilization, as well as application in zero energy buildings are timely explored and summarized. Its advantages lie in the reduction of thermal transmission between the indoor and outdoor environments, the beneficial thermal collection, and the tactful utilization of renewable energy. The optical and thermal properties, as well as the energy performance of liquid flow glazing were found much affected by the glazing and fluid properties, the window configuration, and the operating conditions. These are consequently linked to the degree of electricity saving, the decrease in atmospheric CO2 emission, and the shortened life cycle payback time. The integrated use of solar and geothermal energy in liquid flow glazing systems is also addressed. This leads to more practical studies on the applications in zero energy buildings, such as control, real-time monitoring, and energy management strategies of liquid flow glazing system. In essence, the development of an evaluation platform or database, with systemic classification of liquid flow glazing categories plus the corresponding graded energy saving characteristics, is deemed helpful to the building professionals in meeting the zero energy buildings development targets.

Experimental study of the thermal and energy conservation characteristics of combined phase change material (PCM) room in summer

Combined phase change material room means to lay two different PCMs on building envelops of different orientation. The two PCMs are expected to phase change in summer and winter respectively. In this paper, one combined PCM room and one ordinary room with the same size were built. The thermal characteristics of the two rooms were tested in passive and active conditions. Three cases were designed for the experiment. Case 1 is passive condition. Case 2 is active condition with the air conditioner (AC) working only during the day. Case 3 is active condition with the air conditioner (AC) working only at night. For case 2 and case 3, the set temperature of the AC is 24 °C, 26 °C and 28 °C respectively. During the experiment, indoor air temperature, internal surface temperature, internal surface heat flow and power consumption of the AC were measured. Results showed that in case 1, the PCM room can decrease the indoor air temperature by 6.7 °C during the day. In case 2, when the set temperature of the AC is 26 °C and 24 °C, the PCM room can decrease the indoor air temperature by 0.7 °C and 1.4 °C on average. In case 3, the values are 1.9 °C, 4.5 °C and 5.4 °C respectively when the set temperature is 28 °C, 26 °C and 24 °C. When the set temperature of case 2 is 26 °C and 28 °C, the energy conservation rate is 1.5 % and 36 %, and when the set temperature of case 3 is 28 °C, the value is 1 %. This shows that the combined PCM room has great potential to improve the indoor thermal environment and save energy under both passive and active conditions.

Verification of the numerical analysis using a collocated grid system directly solving the quasi-inviscid incompressible flow around a symmetric airfoil

The present study describes the results of validating a high-quality computational scheme of kinetic energy conservation characteristics under a collocated grid system. In the present study, the pseudo-inviscid incompressible flow around the Kármán-Trefftz airfoil is analyzed. In this analysis, the kinetic energy conservation error is reduced by temporally evolving the governing equation using pressure increments in fractional steps. This sufficient conservation of kinetic energy is validated using an inviscid homogeneous isotropic fluctuation field. The velocity field obtained by this analysis is compared to that of the potential flow obtained using the Kármán-Trefftz airfoil. The numerical analysis is also validated using the lift coefficient profile as a function of a small angle of attack.

Research on energy-saving characteristics of battery-powered electric-hydrostatic hydraulic hybrid rail vehicles

With the advantages of no emission and low noise, battery rail vehicles (BRVs) are widely used in the construction of subway, high-speed railway and so on. However, the problems of low energy efficiency and peak power shock of traction motor have severely restricted the application and promotion of BRVs. To address these problems, an electric-hydrostatic hydraulic hybrid powertrain (EH3) is designed in this paper. Friction braking (FB) is replaced by hydraulic regenerative braking (HRB) and the mode of recovered hydraulic energy coupled at the inlet of pump (ECIP) to assist acceleration is proposed. The energy conservation characteristics of recovery and coupling of hydraulic energy in EH3 powertrain are verified by simulation and laboratory test bench. The energy recovery efficiency of HRB is up to 50% and the new coupling modes can greatly reduce the consumption of electric power. The control strategy is designed to coordinate different working modes which are established based on the high-pressure accumulator (HPA) and the driving state parameters of BRVs. The simulation result shows that the energy consumption of the battery can be reduced by 17.32%. The EH3 powertrain has broad application prospects in realizing energy conservation, reducing peak motor power shock and improving the braking performance of BRVs.

Study on electromagnetic characteristics of plasma model-based on the symplectic multiresolution time-domain scheme

A novel numerical computation scheme, which is symplectic multiresolution time-domain (S-MRTD) scheme, for modeling plasma model is proposed. The loss plasma dispersive model is taken into account in S-MRTD scheme, and the detailed formulations of the proposed S-MRTD scheme are also provided. A one-dimensional perfectly matched layers (PML) are used to terminate the computational domain. The analyses of stability and numerical dispersion demonstrate that S-MRTD scheme is more efficient than traditional finite-different time-domain (FDTD) and MRTD methods. The energy conservation characteristics of S-MRTD scheme in electromagnetic simulation are proved by the propagation of pulse in free space for long-term simulation. In the end, the S-MRTD formulations are confirmed by computing the electric field intensity, reflection and the transmission coefficients for the pulse wave through an unmagnetized plasma slab. A favorable agreement between the numerical solutions is demonstrated, and the efficiency of the proposed scheme is verified. Meanwhile, numerical results show that plasma frequency, collision frequency and thickness are important factors affecting reflection and transmission coefficients.

Research on the control strategy of power train systems for hybrid hydraulic excavators

Hybrid power technology is a practicable method for construction machinery to improve fuel utilization and reduce emissions. In this article, in order to achieve the maximum degree of energy conservation for hybrid hydraulic excavator, a study on a control strategy of the hybrid power train system for a 20-t hybrid hydraulic excavator is conducted. A rule-based method which stabilizes the engine operating points in high-efficiency area and maintains the state of charge of the ultra-capacitor in a feasible operating range is presented. Meanwhile, to improve the reliability of the ultra-capacitor, a two-stage state of charge constraint is applied. To validate the effectiveness of the control strategy, a hybrid power train system simulation loading experiment platform is built. The working characteristics and the energy conservation characteristics of the hybrid power train system are explored. Actual load profiles measured from a 20-t traditional excavator are measured and applied in the system. The experimental results show that the proposed control strategy for the hybrid power train system can improve the fuel economy of the hybrid hydraulic excavator. Meanwhile, dynamic performance of the hybrid power train system is better than that of the traditional excavator.

Energy Efficiency Premiums in Unlabeled Office Buildings

Whether commercial real estate market participants effectively evaluate building energy efficiency characteristics in the absence of a green label has so far remained unaddressed in the literature. I estimate the energy efficiency premium in unlabeled office buildings by exploiting variation in mandatory building energy standard implementations as a result of the 1992 U.S. Energy Policy Act. A more stringent energy code leads to rent and price premiums of approximately 4 percent and 9 percent, respectively. Heterogeneity in the rent premium is also observed based on who pays the utility bills, as would be expected if market participants correctly evaluate energy conservation characteristics. The rent and price premiums are consistent with full capitalization of the energy savings from a more stringent standard.

A memetic algorithm for optimal dynamic design of wireless sensor networks

We present a memetic algorithm that dynamically optimizes the design of a wireless sensor network towards energy conservation and extension of the life span of the network, taking into consideration application-specific requirements, communication constraints and energy consumption of operation and communication tasks of the sensors. The memetic algorithm modifies an already successful genetic algorithm design system and manages to improve its performance. The obtained optimal sensor network designs satisfy all application-specific requirements, fulfill the existing connectivity constraints and incorporate energy conservation characteristics stronger than those of the original genetic algorithm system. Energy management is optimized to guarantee maximum life span of the network without lack of the network characteristics that are required by the specific sensing application.

Adaptive design optimization of wireless sensor networks using genetic algorithms

We present a multi-objective optimization methodology for self-organizing, adaptive wireless sensor network design and energy management, taking into consideration application-specific requirements, communication constraints and energy-conservation characteristics. A precision agriculture application of sensor networks is used as an example. We use genetic algorithms as the optimization tool of the developed system and an appropriate fitness function is developed to incorporate many aspects of network performance. The design characteristics optimized by the genetic algorithm system include the status of sensor nodes (whether they are active or inactive), network clustering with the choice of appropriate clusterheads and finally the choice between two signal ranges for the simple sensor nodes. We show that optimal sensor network designs constructed by the genetic algorithm system satisfy all application-specific requirements, fulfill the existent connectivity constraints and incorporate energy-conservation characteristics. Energy management is optimized to guarantee maximum life span of the network without lack of the network characteristics that are required by the specific application.

Underground water-source loop heat-pump air-conditioning system applied in a residential building in Beijing

In this paper, we report on an underground water-source water-loop heat-pump (UWSWLHP) air-conditioning system for a tall apartment building in Beijing. Water at 14 °C was used as an external low-temperature heat-source. By analyzing field-test data for two years, the authors assessed the operating and controlling conditions of the system. Based on the electricity consumed by public-use air-conditioning power equipment and terminal heat-pumps, the authors put forward an overall evaluation of the energy-conservation characteristics of the system.

Decomposition contact response (DCR) for explicit finite element dynamics

We propose a new explicit contact algorithm for finite element discretized solids and shells with smooth and non-smooth geometries. The equations of motion are integrated in time with a predictor-corrector-type algorithm. After each predictor step, the impenetrability constraints and the exchange of momenta between the impacting bodies are considered and enforced independently. The geometrically inadmissible penetrations are removed using closest point projections or similar updates. Penetration is measured using the signed volume of intersection described by the contacting surface elements, which is well-defined for both smooth and non-smooth geometries. For computing the instantaneous velocity changes that occur during the impact event, we introduce the decomposition contact response method. This enables the closed-form solution of the jump equations at impact, and applies to non-frictional as well as frictional contact, as exemplified by the Coulomb frictional model. The overall algorithm has excellent momentum and energy conservation characteristics, as several numerical examples demonstrate. Copyright © 2005 John Wiley & Sons, Ltd.

Time‐discretized variational formulation of non‐smooth frictional contact

AbstractThe present work extends the non‐smooth contact class of algorithms introduced by Kane et al. to the case of friction. The formulation specifically addresses contact geometries, e.g. involving multiple collisions between tightly packed non‐smooth bodies, for which neither normals nor gap functions can be properly defined. A key aspect of the approach is that the incremental displacements follow from a minimum principle. The objective function comprises terms which account for inertia, strain energy, contact, friction and external forcing. The Euler–Lagrange equations corresponding to this extended variational principle are shown to be consistent with the equations of motion of solids in frictional contact. In addition to its value as a basis for formulating numerical algorithms, the variational framework offers theoretical advantages as regards the selection of trajectories in cases of non‐uniqueness. We present numerical and analytical examples which demonstrate the good momentum and energy conservation characteristics of the numerical algorithms, as well as the ability of the approach to account for stick and slip conditions. Copyright © 2001 John Wiley & Sons, Ltd.

The Darwin Direct Implicit Particle-in-Cell (DADIPIC) Method for Simulation of Low Frequency Plasma Phenomena

We describe a new algorithm for simulating low frequency, kinetic phenomena in plasmas. Darwin direct implicit particle-in-cell (DADIPIC), as its name implies, is a combination of the Darwin and direct implicit methods. Through the Darwin method the hyperbolic Maxwell's equations are reformulated into a set of elliptic equations. Propagating light waves do not exist in the formulation so the Courant constraint on the time step is eliminated. The direct implicit method is applied only to the electrostatic field with the result that electrostatic plasma oscillations do not have to be resolved for stability. With the elimination of these constraints spatial and temporal discretization can be much larger than that possible with explicit, electrodynamic PIC. We discuss the algorithms for pushing the particles and solving for the fields in 2D cartesian geometry. We also detail boundary conditions for conductors and dielectrics. Finally, we present two test cases, electron cyclotron waves and collisionless heating in inductively coupled plasmas. For these test cases DADIPIC shows agreement with analytic kinetic theory and good energy conservation characteristics.

On energy conservation characteristics of autoclaved aerated concrete

Cet article discute nombre d'aspects lies aux caracteristiques de conservation de l'energie du beton cellulaire autoclave (BCA). Nous considerons les aspects suivants: 1. L'effect de la crise de l'energie sur la conception des bâtiments, et l'accent mis de plus en plus sur la conservation de l'energie. 2. Les details sur nombre de proprietes thermiques du BCA. 3. L'importance de l'inertie thermique et du comportement thermique dynamique et les avantages que le BCA a, en comparaison avec l'acier et le beton, en tant que materiau leger pouvant fournir une haute isolation combinee avec une haute inertie thermique. 4. La nouvelle norme californienne sur l'energie avec sa preoccupation pour une utilisation totale de l'energie et la toute nouvelle reconnaissance de l'inertie thermique de la ‘masse legere’. 5. Quelques demonstrations concretes de la consommation d'energie plus faible des bâtiments en BCA en comparaison avec les constructions en bois et en beton arme. 6. Les mesures de l'etancheite a l'air d'un bâtiment en BCA.

Energy resource requirements of a solar heating system

The methods of energy analysis have been applied to a liquid-based, short-term storage solar space and water heating system suitable for a single family dwelling in Toronto. This system, which in many respects represents a worst case for solar heating, takes 1.0–3.5 years of operation to conserve the energy resources required to build, operate and maintain the system. Alternatively, over the twenty year lifetime of the system, the energy resources used indirectly by the solar heating system amount to between 6 and 24% of the direct energy resources conserved by the system. These considerations do not significantly alter the energy-conservation characteristics of the solar heating system unless thermally-generated electricity is used as backup for a 50% solar heating system which replaces oil or gas heating; in this case, only 4–9% of the energy resources are conserved by the solar system. A factor of three variation in energy resource use in collector materials was found in a sample of 7 flat-plate collectors with steel-based collectors using the least. The total energy embodied in the collector was about double that found in the materials alone. The collectors and annual operating energy for the pumps were found to be the two most significant factors in the analysis. An appendix summarizes the energy resource requirements embodied in the materials used for collectors.

Is an electric vehicle in your future?

One solution to the problem of automotive pollution is the electric vehicle (EV). Besides its practically pollution-free operation, it is characterized by low maintenance, fuel economy, and durability. However, the success of the EV depends on the development of a compact, light-weight and inexpensive battery. The short-lived and bulky acid-lead battery limits the EV in terms of speed, range, and size. Among the more promising new technologies are batteries utilizing sodium-sulfur, lithium-sulfide, zinc-air, and zinc-chloride. At present, the EV is capable of providing an efficient means of transportation for short-trip delivery vans, commuter cars, and second family cars. Consumer acceptability is the final major hurdle; promoters should emphasize dollar efficiency of operation and energy conservation characteristics.