Pipeline Diameter Research Articles

SOFTWARE DEVELOPMENT FOR AUTOMATED DESIGN OF FLOW METERS

This work presents the development of a software complex for the automated design of variable pressure drop flowmeters. It includes flowmeters with standard primary devices, namely a diaphragm, nozzles and a venturi tube. To fulfill the task, a review of various software solutions has been conducted. As a result, it was concluded that the existing software does not fully solve the task, because it does not calculate most of the design parameters for metering device. The next stage was a review of the flow rate measuring method by variable pressure drop, and based on it, a mathematical model of flow meters has been implemented taking into account the existing standards. Next, the initial geometric parameters of the flow meter were evaluated and the parameter selection algorithm for the diaphragm with pressure taking chambers was given.
 As a result of the performed analysis, developed software allows you to conveniently enter input parameters, such as flowrate, pressure drop, pipeline diameter, type of constriction device, method of pressure selection, and at the output receive a corresponding schematic image of the flowmeter with all design parameters and the flow calculation formula, based on the pressure difference. For a better understanding of the software operation, an overview of it was offered and an example of a nozzle calculation has been demonstrated.
 The implementation of the created software application makes it possible to increase the accuracy of the accounting of consumed resources, and also reduces time and money costs for measuring instrument development.
 In the future, it is planned to create the software complex by adding to it the design capabilities of calorimetric, ultrasonic flowmeters and rotameters, as well as special software for selecting the most optimal flow measurement method based on the specified parameters of the measured medium, pipeline diameter and flow measurement range.
 Therefore, it will be possible to carry out metrological control and supervision of such measuring complexes, develop and certify methods for measuring the flow of liquids and gases.

Mathematical Modeling of Wax Deposition in Field-Scale Crude Oil Pipeline Systems

The formation of solid wax crystals, which interlock and form a gel-like layer on the inner wall of the crude oil pipeline, influences the transportation of waxy crude oil. The deposited layer grows continuously and hardens during the oil transportation, reducing the effective inside diameter of the crude oil pipeline and the flow rate. In extreme cases, the deposited layer may block the crude oil pipeline leading to a loss of production and capital investment. In this paper, wax deposition from multiphase flow in field-scale oil pipeline transport systems has been studied. The novelty of this work is to develop a mathematical model that incorporates water-in-oil emulsions, wax precipitation kinetics, molecular diffusion, and shear dispersion to enable accurate predictions of both the wax deposit growth rate and aging of the deposit. The coupled nonlinear partial differential equations governing the flow are discretized in time by a second-order semi-implicit time discretization scheme based on the Adams-Bashforth and Crank-Nicolson methods, which completely decouples the computation of the governing equations. The resulting temporal schemes are discretized in space by the bivariate spectral collocation method based on Chebyshev-Gauss-Lobatto grid points and simulated in MATLAB software to obtain the profiles of the flow variables. The simulation results are presented in graphical and in tabular forms and discussed. This study found that the deposit thickness is directly proportional to the Reynolds number and inversely proportional to the mass Grashof number, Schmidt number, and Weber number. Deposit aging is rampant during the early stages of wax deposition, after which it stabilizes at a specific value as time elapses. A deposition model to predict the wax deposit thickness and aging is proposed in this study. The findings of this study will help in making informed decisions on the planning of pigging operations, thermal insulation, and other remediation techniques to be applied in controlling wax deposition in field-scale crude oil pipeline systems.

Pipe inspection robots: a review

Pipelines are one of the safe and most economical ways of transporting fluid matters in industries and households. These pipelines get deteriorated due to aging, internal and external corrosion, and so on. This may cause fluid leakages and may contaminate the environment. So, pipelines are inspected regularly to maintain proper functioning and cost-effectiveness. In-pipe inspection robots (IPIR) that move inside pipelines are widely used to carry out inspection operations. IPIR along with visual and other r non-destructive tests (NDT) are proven to be useful compared to manual inspection. Wheel-driven robots, track-driven robots, wall-press robots, pipe inspection gauge (PIG) robots, and many other bio-inspired designs are available. The design parameters and specializations of each type of robot will be presented in this article. Because each robot is created with different factors in mind, such as pipeline diameter, mobility, adaptability, working conditions, and so on, these robots are unique and have different constraints. These topics will be covered in depth in this article, and will ultimately aid in the selection of certain robots based on specific criteria. New design strategies in the pipe inspection industry that have yet to be explored will also be covered in depth.

Rapid Detection Method of Pipe Inner Diameter Based on Binocular Vision

With the rapid development of robotics, automatic pipeline detection has become a research hotspot in recent years. The existing pipeline diameter automatic detection method needs to calculate a large number of clouds, which is inefficient and difficult to play a role in real-time pipeline detection. Therefore, this paper proposes a fast detection method based on binocular vision to achieve real-time detection of the inner diameter of the pipeline. According to the gradient diagram of the color image after the down-sampling, adaptive double-threshold edge detection is proposed to calculate the edge points. Then an improved BM stereo matching algorithm is proposed to obtain the disparity map of edge points quickly. The least square method is finally used for fitting the edge point coordinates to calculate the inner diameter of the pipeline. The experimental results show that the system has strong accuracy and high efficiency, which can meet the needs of real-time detection of the inner diameter of the pipeline.

Throttle and expansion characteristics of supercritical carbon dioxide during its venting

Supercritical CO2 has important applications in the fields of power cycle generation systems and carbon capture, utilization and storage (CCUS). The venting equipment represents a fundamental pressure-relief method for the purpose of depressurizing sections of those systems for inspection, maintenance or repair. The extremely low temperatures, dry ice blockage and overpressurization will appear in the system due to the throttling and expansion effect during venting. Meanwhile, the released CO2 may cause the exposure for the high density gaseous CO2, solid CO2 particles and cryogenics to the people in the venting area. The study of flow characteristics during CO2 venting is absolutely essential for assessing the hazard probability of dry ice formation and the blockage of relief valves during emergency or routine operational venting. In this paper, the theoretical analysis and experimental tests were conducted to study the throttle and expansion characteristics through the elbow, valve and orifice during straight vertical venting of supercritical CO2 with a 258 m long, 233 mm inner diameter pipeline system. The pressures and temperatures inside the main pipe and vent pipe, and the temperatures near field region were recorded during venting. After the valve was opened, the pressure in the vent pipe rose rapidly, and the rising range decreased with the decrease of the distance from the orifice. The temperature drops of CO2 were obvious after supercritical CO2 passed through the bend, the valve and the orifice. The supercritical CO2 in the main pipe changed into gas-liquid two-phase, and the liquid CO2 were produced in the vent pipe due to the throttling expansion effect. The CO2 temperature near the orifice were in quasi steady state after reaching the lowest value due to the continuous vaporization of liquid-phase CO2 and sublimation of dry ice particles, accompanied by the air entrainment process.

Dimensional effect of CFD analysis for submarine landslides interactions with infinite suspension pipelines

In this study, a computational fluid dynamics method is employed to numerically investigate the impact of submarine landslides with shear-thinning non-Newtonian fluids on infinite suspension pipelines with different diameters at various Reynolds numbers, revealing the influence of the dimensional effect between the small-scale model and the engineering prototype on impact force (i.e., drag and lift forces) coefficients. The study results show that the impact force coefficients increase to varying degrees with the pipeline diameter; the influence of the pipeline diameter on the lift force is significantly higher than that on the drag force; the minimum lift force coefficient for the pipeline diameter of 500 mm is 20.2 times higher than that for the pipeline diameter of 25 mm; and the small-scale model significantly underestimates the impact forces on the prototype, resulting in dangerous submarine pipeline designs. With increasing pipeline diameter, the slumping phenomenon clearly occurs in submarine landslides due to the gravitational potential energy and it causes a rapid increase in the head velocity of the landslide, thereby significantly increasing the impact force coefficients, especially for pipelines with large diameters. Furthermore, in gravity-free simulations, the impact force coefficients decrease with increasing pipeline diameter. This is because when the impact velocity is large and the pipeline diameter is small, submarine landslides have a high shear rate on the pipeline, resulting in high frictional stresses. Notably, the influence of dimensional effects needs to be considered to determine the velocity and shear rate of the submarine landslides around/on pipelines.

Low-Cost Representative Sampling for a Natural Gas Distribution System in Transition.

Natural gas distribution systems within municipalities supply a substantial fraction of energy consumed in the United States. As decarbonization of the natural gas system necessitates new modes of operation outside original design purposes, for example, increased hydrogen or biogas blending, it becomes increasingly important to understand in advance how existing infrastructure will respond to these changes. Such an analysis will require detailed information about the existing asset base, such as local soil composition, plastic type, and other characteristics that are not systematically tracked at present or have substantial missing data. Opportunistic sampling, for example, collecting measurements at assets that are already undergoing maintenance, has the potential to substantially reduce the cost of gathering such data but only if the results are representative of the full asset base. To assess prospects for such an approach, we employ a dataset including the entire service line and leak database from a large natural gas distribution utility (∼66,700 km of service pipelines and over 530,000 leaks over decades of observations). This dataset shows that service lines affected by excavation damage produce an approximately random sample of plastic and steel service lines, with similar distributions of component age, operating pressure, and pipeline diameter, as well as a relatively uniform spatial distribution. This means that opportunistic measurements at these locations will produce a first-order estimate of the relative prevalence of key characteristics across the utility's full asset base of service lines. We employ this approach to estimate the plastic type, which is unknown for roughly 80% of plastic service lines in the database. We also find that while 32% of leaks across all components occur in threaded steel junctions, excavation damage accounts for 75% of hazardous grade 1 leaks in plastic service lines and corrosion accounts for 47% in steel service lines. Insights from this sampling approach can thus help natural gas utilities collect the data they need to ensure a safe and reliable transition to a lower-emission system.

Prediction of Mixing Uniformity of Hydrogen Injection inNatural Gas Pipeline Based on a Deep Learning Model

It is economical and efficient to use existing natural gas pipelines to transport hydrogen. The fast and accurate prediction of mixing uniformity of hydrogen injection in natural gas pipelines is important for the safety of pipeline transportation and downstream end users. In this study, the computational fluid dynamics (CFD) method was used to investigate the hydrogen injection process in a T-junction natural gas pipeline. The coefficient of variation (COV) of a hydrogen concentration on a pipeline cross section was used to quantitatively characterize the mixing uniformity of hydrogen and natural gas. To quickly and accurately predict the COV, a deep neural network (DNN) model was constructed based on CFD simulation data, and the main influencing factors of the COV including flow velocity, hydrogen blending ratio, gas temperature, flow distance, and pipeline diameter ratio were taken as input nodes of the DNN model. In the model training process, the effects of various parameters on the prediction accuracy of the DNN model were studied, and an accurate DNN architecture was constructed with an average error of 4.53% for predicting the COV. The computational efficiency of the established DNN model was also at least two orders of magnitude faster than that of the CFD simulations for predicting the COV.

Modeling transient cavitating flow in large drop crude oil pipelines

Transient cavitating flow is a dangerous condition in the operation of large drop crude oil pipelines. Accurately predicting the high pressure generated by cavity collapse is the premise of analyzing and formulating pipeline safety management and control strategies. A new numerical simulation method for one dimension cavitating flow in crude oil pipelines considering the effect of unsteady friction was proposed. The unsteady friction (UF) term is coupled to the classical discrete gas cavity model (DGCM) for modeling the cavitating flow, and the proposed model is called UF-DGCM. The method of characteristics (MOC) is used to solve the UF-DGCM. The validity of the model has been verified with experimental data. The pipeline length of the two test cases is 37.23 m and 15.22 m, respectively, and the pipeline diameter is 22.1 mm and 20.0 mm, respectively. For the two test cases, the accuracy of the prediction results is improved by 6.7% and 4.4%, respectively. A case study of cavitating flow caused by pump shutdown in a pipeline with a length of 35 km and a diameter of 738 mm was performed using UF-DGCM, and the effects of water hammer wave speed, crude oil vapor pressure, and pump shutdown time on cavitating flow were analyzed. The results show that the maximum pressure peak is dependent on the water hammer wave speed. About the increase in the wave speed value of 200 m/s will lead to an increase in the maximum pressure head value of 10.1 m. The increase of pump shutdown time will inhibit the growth of cavities, and increasing the pump shutdown time by 4 s will shorten the existence time of cavities by about 3 s. The extension of the pump shutdown time will prevent cavitating flow. The proposed improved model is more suitable for transient cavitating flow analysis, and the results of flow parameters research will be helpful to prevent cavitating flow in crude oil pipelines.

Simulation analysis of the effect of single-chamber double-line pipe jacking through different soil materials on surface uplift and subsidence.

This article is based on the relocation project of the 330 kV overhead line in Xi’an, China. In this paper, the soil settlement under different jacking depths was calculated by using the modified Peck’s formula. Meanwhile, by modeling in ABAQUS, the jacking process of a single-chamber double-line large diameter pipeline under different soil conditions was simulated, and the ground deformation data under the different simulated working conditions were obtained. The results of the two methods were compared with the construction monitoring results, and it was found that the finite element simulation results were closer to the actual results. The control variable method was used in the analysis of the surface soil deformation law to analyze the effect of different soil parameters and pipe jacking depths on surface soil deformation. Finally, the best soil conditions applicable to single-chamber double-line large diameter pipe jacking construction were obtained through comparative analysis. The results show that (1) when using double-line construction, the maximum surface settlement under different soil conditions is located 11–15 m from the centerline of the soil above the pipeline, the minimum settlement location is inside the isolation pile, and with the increase in jacking distance, the settlement at the same section of the surface will gradually decrease and finally produce a small uplift. (2) In the first jacking, the settlement of powder clay is the largest, and the maximum settlement points in the surface section are more distributed. The maximum settlement value is approximately 11.66 mm. The settlement of powder soil is the smallest but produces a certain uplift deformation, and its maximum settlement is more concentrated in the surface section. After the comparison of deformation and soil parameters, loess-like soil is more suitable for single-compartment double-line large diameter pipe jacking construction. (3) When the top pipe burial depth changes, the greater the burial depth is, the smaller the settlement but the greater the lateral influence range. In the soil parameters, the modulus of elasticity only changes 3 MPa, and the settlement change value is approximately 5 mm. By changing the parameters, it can be obtained that the larger the modulus of elasticity of the soil is, the smaller its deformation. The larger the internal friction angle of the soil is, the smaller its deformation, but the maximum value of settlement change is only 1.7 mm, which means that the change in the internal friction angle has little effect on the soil deformation.

Significance of hydrodynamic cavitation to enhance reuse of secondary sedimentation tank effluent: a geometrical assessment

ABSTRACT Adequate wastewater management is an environmental concern because of the lack of freshwater resources, which brings about the quick augmentation of technologies for complete quantitative and qualitative wastewater recovery. In the cluster of the advanced oxidation process, hydrodynamic cavitation developed as a promising technology to treat wastewater, in the last couple of decades, due to its low-cost energy efficiency without aided and residual chemicals. In the present study, two pilot-scale experimental setups (I and II) of hydrodynamic cavitation reactor have been used to treat the secondary sedimentation tank (SST) effluent of natural six sewage treatment plant (STP) of Surat city for irrigational reuse, using an orifice as a cavitating device. At inception, the inlet pressure has been optimized, which follows the first-order kinetic rate constant. The pump power with respect to the diameter of the main pipeline has differentiated by keeping the constant dimension of the cavitating device to compare the geometrical effect and was analyzed using the number of rotations concerning recirculation time to degrade the chemical oxygen demand (COD). It is found that the maximum COD, total suspended solids (TSS), and most probable number (MPN) were degraded to 79.8%, 63.8%, and 99.5%, respectively, by setup II; also, descent within the permissible limit proclaimed by CPHEEO India to irrigate the non-edible crops.

Peak force coefficients on small-diameter spanning pipelines under waves

This paper reports an experimental investigation undertaken to measure the peak force coefficients for small-diameter pipelines (cables and umbilicals) spanning over rocky, uneven seabed under regular wave conditions. The free spans formed by the uneven bed are investigated by modelling multiple regularly spaced free spans (referred to as multi-span) in a flume. Approximately 600 physical tests were conducted to quantify the effects of gap height to pipeline diameter ratio G and the span length to pipeline diameter ratio S on the peak force coefficients. The Keulegan–Carpenter number KC and Reynolds number Re p tested were in the range 20 ≤ KC ≤ 2000 and 5 × 10 3 ≤ Re p ≤ 10 5 , respectively. The ratios between the peak force coefficients for the multi-span configuration and a uniform-span configuration ( S → ∞) are demonstrated to be a function of S /[( S + C ) G ], where C is the contact ratio, defined as the distance between two adjacent free spans divided by the pipeline diameter. Combined with the peak force coefficients under uniform-span conditions obtained from the present experiments, this finding enables the peak force coefficients under a multi-span condition to be reasonably estimated. • Peak force coefficients for fully spanning small-diameter pipelines subject to waves are provided based on a number of physical tests with KC up to 2000. • Quantification method for the peak force coefficients under the effect of multiple free spans is proposed. • The scattered seabed roughness and the multiple free spans lead to significant reductions in the peak force coefficients.

Research on the influence of secondary heat network characteristics on wind power consumption in the combined electric and heat system

With the large-scale investment of thermal power units in the “Three Norths” area, the coupling of the combined electric and heat system has become more and more close, leading to a huge number of abandoned wind. On the basis of the traditional thermal system model, physical characteristics of the secondary heat network are added, and an optimal scheduling model of the combined electric and heat system considering the operation characteristics of the secondary heat network is established. The influence of the operation characteristics of the secondary heat network on the heat loss and wind power consumption of the thermal system is studied. Based on this, different conditions are set up to study the influence of heat-exchange efficiency of heat exchange stations and the diameter of secondary heat network pipes on the combined electric and heat system. The simulation analysis shows that the heat network characteristics of the secondary heat network need to be considered in the scheduling analysis of the combined electric and heat system. In addition, the system air curtailment rate can be reduced by improving the heat exchange efficiency of the heat-exchange station and changing the diameter of the secondary heat network pipeline.

Safety assessment of concrete pipeline considering the effect of pipe diameter subjected to blasting vibration

Urban concrete pipelines are prone to damage in blasting projects such as excavation of adjacent metro tunnels. Therefore, it is necessary to evaluate the safety of buried concrete pipeline subjected to blasting vibration. Based on the field blasting test of full-scale buried concrete pipeline, considering the factor of pipeline diameter, the dynamic response of concrete pipelines with different diameters was studied by using finite element software ANSYS/LS-DYNA. According to dimensional analysis, a prediction model of particle peak velocity (PPV) considering pipeline diameter was established. Combined with the tensile strength of concrete, the safety criterions of PPV for concrete pipeline with different diameters were proposed, which provided guidance for actual blasting.

Solid–liquid two-phase flow in deep-sea mining pipelines based on CFD–DEM

ABSTRACT Owing to the scarcity of terrestrial mineral resources, deep-sea mining has gradually become a popular topic of research. As a feasible solution for deep-sea mining, pipeline transportation has become increasingly important. Here, the CFD–DEM framework is used to study the flow law of particles of different sizes in deep-sea mining pipelines. The numerical results, which were verified by experiments, indicated that the particle size must be less than 1/3rd of the diameter of the mining pipeline.

Elastic Obstacle-Surmounting Pipeline-Climbing Robot with Composite Wheels

Regular inspection and maintenance can ensure safe working conditions of transport pipelines without leakage and damage. Pipeline-climbing robots can be used for rapid inspection of pipelines, effectively reducing labor costs and time consumption. For the annular pipelines outside spherical tanks, the special distribution and installation form presents more high obstacles, and puts forward higher requirements for the robot’s climbing performance and obstacle-surmounting ability. An elastic obstacle-surmounting pipeline-climbing robot with composite wheels is proposed in this paper. The designed elastic shock-absorbing suspension mechanisms and composite wheels were designed to increase the stability and obstacle-surmounting ability of the robot. The adjustable robot frame and rotating joint mechanisms allowed the robot to adapt to pipelines of different diameters and radians. Force analysis and simulation of obstacle surmounting by the robot were performed. Experiments were conducted on a 110-mm diameter pipeline to test the payload performance and obstacle-surmounting ability of the robot. With its elastic shock-absorbing suspension mechanisms, the pipeline-climbing robot could carry a 30 kg payload and stably climb the pipeline. The maximum height of obstacles surmounted by the composite wheels of the robot was 20 mm. In the process of surmounting obstacles, the velocity and inclination angle of the robot could remain relatively stable. This novel composite wheels and mechanisms can improve the performance of the pipeline-climbing robot and solve the problem of surmounting high obstacles. By carrying various equipment and instruments, the robot can promote the automated maintenance and inspection of complex pipelines.

Experimental Study of the Effect of Backfill Conditions on Soil Responses around a Pipeline under Wave–Current Load

Waves and currents coexist widely in the ocean, and the interaction of waves and currents plays an important role in the instability of submarine pipelines. So far, most studies have concentrated on discussing the dynamic reaction within the seabed around a pipeline under pure wave action, monotypic sediment, and an exposed or fully buried condition. In this study, the effect of current characteristics (e.g., current velocity and propagation direction) and backfilling conditions (e.g., backfill depth and sand property) on the dynamic response around the submarine pipeline is investigated by conducting laboratory experiments. Pipeline was buried in the excavated trench using three types of sand with the median size of 0.150 mm, 0.300 mm and 0.045 mm, respectively. Five relative backfilled depths, with the ratios of backfill depth over the pipeline diameter being 0, 1/2, 1, 3/2 and 2, were tested. The excess pore pressure was measured simultaneously by using the pore pressure sensors installed around the pipeline surface and beneath the pipeline. Results show that both the pore pressure amplitude and its descent rate gradually decrease with an increasing backfill depth, which decreases the soil liquefaction potential. Under the co-current actions, the decrease rate of the pore pressure along the vertical direction increases with an increasing current velocity. However, the increased current velocity leads to a decrease of the attenuation rate under the counter-current actions compared with the pure wave actions, and the counter-current effect on the pore pressure within the seabed is greater than the co-current. The results indicate that the dynamic response around the pipeline in coarse sand is close to that without the backfill scenario, even if the backfill depth reaches up to two times that of the pipeline diameter. It is found that the larger the median particle size of backfill sand, the smaller the impact on pore pressure within the seabed beneath the pipeline.

Optimal diameter of liquid-phase ethane transportation pipeline considering the liquid-vapor phase change

The liquid-phase pipeline is the optimal choice for large-amount and long-distance ethane transportation. Selecting the optimal diameter is necessary for the economical design of the pipeline. However, the special critical temperature 32.2 °C and critical pressure 4.87 MPa of ethane makes it easy to become liquid-vapor phase change, which is not considered in the traditional natural gas or crude oil pipeline design. In this paper, a new mathematical model is built to calculate the optimal diameter of the ethane pipe by using the ‘pump station + pipeline’ unit as the research object. The model selects the lowest total pipeline construction and operation costs as the objective function, and the constraints include the ethane liquid-vapor phase change, the pipe maximum allowable stress, and pipe specifications. In particular, the liquid-vapor phase change constraint is added to the traditional model to avoid the ethane liquid-vapor phase change, which is obtained by quantitatively analyzing the variation of physical parameters of ethane close to the pressure-temperature phase boundary. The optimization model is solved by use of the genetic algorithm. Finally, optimal pipe diameters are calculated for the conditions of transmission capacity from 1000 t/d to 10,000 t/d. Comparisons of calculated pipe diameter with eight actual cases show that the results are feasible with the average and maximum deviations being less than 5% and 8%, respectively. The effects of pipe materials and electricity prices on the pipe diameter are analyzed. It is demonstrated that the pipe material has a negligible effect on the optimal diameter, whereas increasing the electricity price will lead to the increase of the optimal diameter in the case of large transmission volumes.

АЛГОРИТМ РАСЧЕТА СОВМЕЩЕННОЙ ЗАКРЫТОЙ ОСУШИТЕЛЬНО-УВЛАЖНИТЕЛЬНОЙ СЕТИ В СОСТАВЕ ОСУШИТЕЛЬНО-УВЛАЖНИТЕЛЬНЫХ СИСТЕМ

The aim of the research is to develop an algorithm for calculating the combined closed drainage and humidification network as part of the drainage and humidification systems. The technical literature was used as the main source material for the calculation of closed collectors of drainage systems and closed pressure pipelines. The construction of the algorithm was carried out in accordance with the provisions of GOST 19.701-90 (ISO 5807-85). To develop a general algorithm for calculating a combined closed drainage and humidification network, a procedure was drawn up for calculating the lengths of collector sections according to the ac-cepted diameters and a procedure for calculating the diameters of humidifying pipelines in the form of an algorithm, while the calculated dependencies were used from publicly available sources. A calculation scheme for a combined closed drainage and humidification network and a form for outputting the calculation results have been developed. The developed algorithm includes the calculation of the diameters of the collectors for the drainage drainage and the diameters of the humidification pipelines for supplying water for humidification, as well as the coordination of the diameters of the drainage collectors and humidification pipelines

Temperature Waves Phase Optimal Time Lag in the Refrigerated Warehouse Thermal Insulation

The thermal inertia of the wall manifests itself as a damping of amplitude (Decrement Factor) as well as a temperature wave phase lag (Time Lag) upon its passing through the wall. The objective of the research was to highlight the utilization prospects of these phenomena in the building envelops of large refrigerated warehouses. Numerical methods were used for nonlinear, non-stationary processes simulation. The relationship of the refrigeration cycle to the thermo-insulating walls of the cold store in the conditions of daily external temperature oscillations and solar radiation flux has been studied. As the ambient temperature rises, the power efficiency of the refrigeration cycle is decreasing and the need to increase the compressor displacement is growing. If the value of the phase delay in the wall is optimum, the daily minimum of the heat leakage through the wall enters the chamber with the phase shift for the period of maximum daily external temperature. This enables to smooth out the daily oscillations amplitudes of the heat load of the refrigerating machine as well as compressor power rating and to approximate their peak values closer to the average daily ones. The study had been concluded by demonstrating the possibility of reduction in: heat exchange areas for both condenser and evaporator, receiver volume, diameter of pipelines, material cost. Better conditions for temperature stabilization in the cold store will enhance the keeping quality and prolong the food products shelf life.