Direct Expansion Method Research Articles

The evaluation system for intelligent recycling of cold energy from LNG vessels

Through the study of LNG ship cold energy intelligent recycling technology, the analysis of ship propulsion efficiency improvement and LNG cold energy residual energy intelligent recycling is carried out to explore and solve the technical problems of imperfect cold energy recycling in LNG ship cold energy intelligent recycling technology. LNG ship cold energy intelligent recycling uses the combination of dual-fuel propulsion technology and LNG cold energy residual energy recycling technology. The LNG ship cold energy intelligent recycling technology uses various methods such as the direct expansion method, Rankine cycle method of the intermediate medium, and combined method to solve most of the power supply problems on the ship.

EXERGY ANALYSIS OF LIQUID AIR ENERGY STORAGE SYSTEM BASED ON LINDE CYCLE

The paper presents a theoretical analysis from an energetic and exergetic point of view for a liquid air energy storage system (LAES). This paper identifies upper bounds on the energy and exergetic efficiency for this system. The system uses the simple Linde-Hampson liquefaction cycle for the liquefaction subsystem and the direct expansion method without heating above ambient temperature, for the power generation subsystem. It is known that as the temperature decreases, the destruction of mechanical work input increases due to the irreversibility of working processes. As a result, any irreversible process is very important to observe in cryogenic processes. The purpose of this paper is to develop an exergetic analysis which is then used in a procedure to optimize the Linde installation within the liquid air energy storage system when some functional parameters are changed. The analysis aims to find the functional parameters for which the exergetic efficiency of the installation is maximum. For each subsystem of the simple Linde installation an exergetic product and a fuel were defined and, based on their definition, the coefficient of performance of each functional area was calculated as well as the exergy destructions. Finally, the analysis of system components is presented in order to identify the components that have the greatest impact on energy and exergetic efficiency in an ideal environment. The analytical approach presented in this paper can be applied to other LAES configurations to identify the optimal operating points in terms of energy and exergetic efficiency.

Improvement in fatigue performance of thin fasteners via electromagnetic strengthening process

The fatigue behaviors of 1.5 mm-thick 2A12-T4 aluminum alloy fasteners processed by the electromagnetic cold expansion (EMCE) method are studied. The fatigue life of the fasteners processed by the EMCE method is 1.77 times that of the conventional direct mandrel cold expansion method at the maximum applied stress of 120 MPa. Finite element simulation shows that the EMCE process can introduce tensile stress in both hoop and radial directions, which avoids warping in thin fasteners. Moreover, the EMCE process achieves uniformly distributed compressive residual stress along the thickness direction, which is also beneficial to the fatigue improvement of the fasteners.

Air conditioning performance of a ground source heat pump that use direct expansion method

Air conditioning performance of a ground source heat pump that use direct expansion method

A class of lattice Boltzmann models for the Burgers equation with variable coefficient in space and time

<abstract><p>In this paper, we study the numerical results of the Burgers equation with the variable coefficient in space and time and then put forward a lattice Boltzmann model of backward difference solution of nonlinear system. The macroscopic equation is recovered by using the Chapman-Enskog method and the direct Taylor-series expansion method. These two methods can recover the same hydrodynamic equations and analyze various nonlinear systems. In particular, it is much easier to perform error analysis by using the direct Taylor method. In this study, the two methods are used to analyze the Burgers equation with variable coefficient in space and time, the numerical results are discussed and are compared with the analytical solution. The numerical results verify the effectiveness of the model. The stability of the model ensures that we can use larger time step lengths. The improvement of lattice speed can improve the computational performance of the model, and the D1Q7 lattice performance is much better than the D1Q5 lattice performance.</p></abstract>

Heat exchange performance of ground source heat pump that use direct expansion method

Heat exchange performance of ground source heat pump that use direct expansion method

Heat exchange performance of ground source heat pump that use direct expansion method

Heat exchange performance of ground source heat pump that use direct expansion method

Heat exchange performance of ground source heat pump that use direct expansion method

Heat exchange performance of ground source heat pump that use direct expansion method

Hot water supply performance of a ground source heat pump that use open-type direct expansion method

Hot water supply performance of a ground source heat pump that use open-type direct expansion method

Design Technique for a Shaped-Reflector Antenna With a Three-Layer Cable Net Structure

Considering the contoured beam design technique applied to deployable mesh reflector antennas, this article presents a design method for a shaped reflector with a three-layer cable net configuration. First, the concave-convex surface of the mesh reflector antenna required to meet the far-field pattern in an area of interest is designed based on the direct expansion method. Then, a typical application of a rotationally symmetric reflector is designed and analyzed to produce a coverage beam for the continental United States (CONUS). Second, an improved geometry for the three-layer cable net is established by the design scheme. Next, the pretension iterative optimization of the three-layer-shaped cable net structure is carried out by combining the equilibrium matrix method and a topology optimization method. Finally, using the design results of this article as a manufacturing case, we develop a prototype and measure the shape accuracy of the mesh-shaped reflector. The experimental results indicate that the far-field pattern of the prototype contoured beam antenna is close to the computations, which demonstrates the correctness and effectiveness of the proposed design technique.

Heat exchange performance of ground source heat pump system that use direct expansion method

Heat exchange performance of ground source heat pump system that use direct expansion method

Study on Ground Source Heat Pump That Use Direct Expansion Method Using Foundation Pile

Study on Ground Source Heat Pump That Use Direct Expansion Method Using Foundation Pile

Study on underground heat exchanger for ground source heat pump that use direct expansion method

Study on underground heat exchanger for ground source heat pump that use direct expansion method

Operating Range for a Combined, Building-Scale Liquid Air Energy Storage and Expansion System: Energy and Exergy Analysis

This paper presents the results of an ideal theoretical energy and exergy analysis for a combined, building scale Liquid Air Energy Storage (LAES) and expansion turbine system. This work identifies the upper bounds of energy and exergy efficiency for the combined LAES-expansion system which has not been investigated. The system uses the simple Linde-Hampson and pre-cooled Linde-Hampson cycles for the liquefaction subsystem and direct expansion method, with and without heating above ambient temperature, for the energy production subsystem. In addition, the paper highlights the effectiveness of precooling air for liquefaction and heating air beyond ambient temperature for energy production. Finally, analysis of the system components is presented with an aim toward identifying components that have the greatest impact on energy and exergy efficiencies in an ideal environment. This work highlights the engineering trade-space and serves as a prescription for determining the merit or measures of effectiveness for an engineered LAES system in terms of energy and exergy. The analytical approach presented in this paper may be applied to other LAES configurations in order to identify optimal operating points in terms of energy and exergy efficiencies.

Scanning PIV Method and Its Application to the Calorimetry of Ground Source Heat Pump Systems

Ground source heat pump (GSHP) systems that use a direct expansion method are expected to have higher energy-saving performance than conventional air conditioning systems. The heat transfer rate is evaluated by measuring the temperature, humidity, and flow rate at the indoor unit of the GSHP system. However, it is difficult to evaluate the flow rate by measuring the flow velocity distribution at the outlet of the indoor unit. In this study, the Scanning PIV method is proposed to improve the accuracy of the flow rate measured by hot wire anemometers. The flow rates obtained by the hot wire anemometers were 60.6% and 15.2% higher than those from the PIV method during cooling and heating operation, respectively. Compensation formulas are generated using the results of the Scanning PIV method to correct the measurements from the hot wire anemometers. This compensation formula reduced the error generated by the nonuniformity of velocity distribution. It was 60.6% to 2.5% in cooling operation and 15.2% to 0.9% in heating operation, respectively. The compensation formulas were applied to evaluate the performance of a GSHP system, and the result shows that the GSHP system provides improved performance stability compared to traditional air conditioning systems.

直接膨張方式地中熱ヒートポンプの性能評価

The purpose of this study is to investigate the performance of a ground source heat pump using direct expansion method in case of hot water supply system. The underground temperature beneath about 10m maintains almost constant throughout a year. Ground Source Heat Pump (GSHP) utilizes this property. GSHP using direct expansion method has higher performance than GSHP using indirect heat exchanger method. GSHP using direct expansion method can also be reduced the number of parts and initial cost. GSHP using direct expansion method is difficult to evaluate the power of heating in the refrigerant side because the refrigerant becomes two phase flow and it reduces the measurement accuracy of flow rate. Therefore, we tried to evaluate the performance on GSHP using direct expansion method as hot water supply system. We get the amount of heat was evaluated by measuring the temperature difference and flow rate of supplying hot water. We used the closed loop vertical borehole which depth was 30m. Average of COP became 3.1.

直接膨張方式地中熱ヒートポンプに用いる地中熱交換器の性能

The Ground Source Heat Pump (GSHP) utilizes a stable heat source existing in underground shallower than 150m. Because of that, we are making highly efficient driving possible throughout the year regardless of climate. Other features of GSHP need high initial cost, but the running cost is low. The direct expansion method GSHP used in this study directly exchanges heat with the underground heat via the copper pipe filled with the refrigerant using the underground heat exchanger. For the reason, it can operate with higher efficiency than indirect system GSHP which has already been put into practical use. In the previous experiments, the performance was evaluated by using one borehole. However, in order to cope with the increase in output of the outdoor unit, two boreholes were used, and the heat exchange performance in the case of installing the underground heat exchanger in parallel examined. COP was used to evaluate heat exchange performance. The average value of COP was about 3.1.The main reason for the low COP value think that the refrigerant piping length of the borehole and outdoor unit is long.

A double expansion method for the frequency response of finite-length beams with periodic parameters

A double expansion method for the frequency response of finite-length beams with periodic distribution parameters is proposed. The vibration response of the beam with spatial periodic parameters under harmonic excitations is studied. The frequency response of the periodic beam is the function of parametric period and then can be expressed by the series with the product of periodic and non-periodic functions. The procedure of the double expansion method includes the following two main steps: first, the frequency response function and periodic parameters are expanded by using identical periodic functions based on the extension of the Floquet-Bloch theorem, and the period-parametric differential equation for the frequency response is converted into a series of linear differential equations with constant coefficients; second, the solutions to the linear differential equations are expanded by using modal functions which satisfy the boundary conditions, and the linear differential equations are converted into algebraic equations according to the Galerkin method. The expansion coefficients are obtained by solving the algebraic equations and then the frequency response function is finally determined. The proposed double expansion method can uncouple the effects of the periodic expansion and modal expansion so that the expansion terms are determined respectively. The modal number considered in the second expansion can be reduced remarkably in comparison with the direct expansion method. The proposed double expansion method can be extended and applied to the other structures with periodic distribution parameters for dynamics analysis. Numerical results on the frequency response of the finite-length periodic beam with various parametric wave numbers and wave amplitude ratios are given to illustrate the effective application of the proposed method and the new frequency response characteristics, including the parameter-excited modal resonance, doubling-peak frequency response and remarkable reduction of the maximum frequency response for certain parametric wave number and wave amplitude. The results have the potential application to structural vibration control.

A twice expansion analysis method in the time-domain for wave action on a floater translating with a large amplitude

A twice expansion method in the time-domain was proposed for computing wave interaction with a body experiencing large amplitude drift motion. The body displacement was divided into two components, a low frequency and a high frequency oscillations. The low frequency oscillation was computed by a wavelet transform method with time matching in the computation, and was called as the instantaneous mean position. Then the first and the second order boundary conditions were established at the instantaneous mean position and the still free surface by a perturbation expansion method which would guarantee that the expansion factors are always small. The velocity potential was separated into the incident, the scattering and the steady disturbance potentials. The scattering and the steady disturbance potentials were computed by solving integral equations respectively. Numerical examinations were carried out for a forced moving truncated cylinder in waves and wave interaction with a spar platform with mooring system in deep water. The comparisons were made between the results from the present twice expansion method and the direct expansion method. The comparisons show that the present method can consider the changes in the phase and the encounter frequency of wave loads due to body drift motion at low frequency. The body response at the natural frequency of the spar platform from the twice expansion method is smaller than that from the direct expansion method, but is larger at lower frequency. The peak frequency of the response amplitude from the present method moves to lower frequency, as the influence of wave drift damping is included in the model.

直接膨張方式地中熱ヒートポンプシステムの性能評価

The purpose of this study is to investigate the performance of a ground source heat pump (hereafter, GSHP) using direct expansion method in case of hot water supply system. The underground temperature beneath about 10m maintains almost constant throughout a year. The GSHP utilizes this constant temperature. The GSHP using direct expansion method has higher performance than the GSHP using indirect heat exchange method. The GSHP using direct expansion method can also be reduced the number of parts and initial cost. However, the GSHP using direct expansion method is difficult to obtain an amount of heat removed in a refrigerant side because the refrigerant becomes two phase flow and it reduces the measurement accuracy of flow rate. Therefore, we tried to evaluate the performance of the GSHP using direct expansion method as hot water supplying system. The amount of heat removed was evaluated by measuring the temperature difference and flow rate of supplying hot water. We used the closed loop vertical borehole whose depth was 30m. In the case that the setting temperature of hot water was 45°C, the heating time was 7 hour 46 minutes and time averaged COP was 3.29.