Cold Circulation Research Articles

Calculation and utility analysis of lychee life-cycle carbon emissions considering food loss and waste

Food loss and waste become the sever problem in the modern society. This paper studies the carbon emissions related to different circulation forms of lychee，which is a typical perishable fruit in China. First, we construct a kinetic model of lychee by using the Arrhenius equation. And then, we propose a carbon emission measurement with the unit effective carbon emission and the comprehensive carbon emission utility by using life cycle assessment. With this measurement, we measure the rate of loss and life cycle carbon emissions of four lychee's circulation scenarios, including: cold chain, room temperature, cold chain broken at the beginning and cold chain broken at the end.The results show that with the traditional carbon emission measurement, the carbon emissions generated by the cold chain circulation scenario are the highest in total carbon emissions under the four scenarios. But using the unit effective carbon emissions measurement, the total carbon emissions under the cold chain circulation situation is 34.84 % less than those of the room temperature circulation. Under the cold chain circulation scenario, the unit effective carbon emission and comprehensive carbon emission utility are 0.38 kgCO2/kg and 85.33 %, respectively. Improving the rate of cold chain circulation can improve the comprehensive carbon emission utility and achieve land-saving. Comparing with the cold chain circulation rate in China in today, when it increases to 95 %, the comprehensive carbon emission utility of lychee supply chain increases to 81.65 %, and the required land is reduced by 54.84 %.

Hydrodynamics of a cold circulating fluidized bed for methanol-to-olefins (MTO) process: experimental and computational investigation

The present study aims to investigate the hydrodynamic behavior of gas–solid flow in a pseudo-two-dimensional cold circulation fluidized bed specifically designed to mimic a plane cut of an industrial methanol-to-olefins (MTO) bed. The solid velocity pattern was experimentally examined using the Particle Image Velocimetry with Digital Image Analysis (PIV-DIA) technique. The hydrodynamics of this pseudo-2D bed were studied using the twoPhaseEulerFoam solver in OpenFOAM, and the adjusted solver was validated through solid particle velocity and solid volume fraction comparisons, showing good agreement with experimental data. Additionally, the study explores different geometries, including symmetric and asymmetric baffles, to understand their impact on the mixing characteristics of the circulating fluidized bed for MTO. The findings highlight the significant role of asymmetric baffles in enhancing mixing behavior. Furthermore, the DIA technique was employed to study the effects of bubbles on gas–solid mixing, revealing that the low mixing region of the bed limited the diameter of bubbles.

Development and test: Future-proof substation designs for the low-temperature operation of domestic hot water systems with a circulation loop

On the transition toward low-temperature district heating (DH), generation sectors, distribution networks, and building consumers should all be adapted to low-temperature operation conditions. However, a bottleneck in lowering DH return temperatures is the domestic hot water (DHW) system with a circulation loop in multifamily buildings. Existing systems with a single heat exchanger often led to elevated return temperatures because of the reheating of the circulation loop. This study developed several innovative designs for future-proof DHW substations that decouple the heating of cold water and circulation flows, ensuring lower DH return temperatures in large multifamily buildings. First, a theoretical analysis was performed for benchmarking the return temperature for various proposed design configurations under low-temperature operation conditions; then, the proposed configurations were tested for a Danish multifamily building connected to a medium–low-temperature DH network. In the field tests, compared to a typical DHW substation with a single heat exchanger, the proposed configuration with the circulation loss booster reduced the average DH return temperature from 46.4 °C to 34.1 °C and 27.9 °C for parallel or serial connections, respectively. Economic analysis confirms the viability of the proposed solution, with a payback period ranging from 3.4 to 7.9 years.

A fully coupled thermo-poro-elastic model predicting the stability of wellbore in deep-sea drilling. Part A: Analytic solutions

Wellbore stability is important to deep-sea drilling (DSD) for exploiting offshore oil and gas resources. Accurate prediction of the mechanical behaviors of rock formation around the wellbore can effectively prevent wellbore failure via adjusting mud weight. In this paper, a fully coupled thermo-poro-elastic (THM) model is developed by combining fluid circulation in the wellbore and rock deformation in the reservoir. Transient heat transfer in the wellbore/reservoir and heat exchange between the tubing, annulus, riser, casing, cement, seawater and rock formation are considered. By decomposing the problem into axisymmetric and antisymmetric sub-problems, the analytical solutions for transient temperature, pressure and stress in the rock formation and fluid temperature changes in the drill pipe, annulus and seawater near the riser are obtained and validated against with the numerical solutions, existing fluid circulation model, field measurement data and the existing model without considering fluid circulation. After that, a typical case study is carried out to show the mechanical behavior around the wellbore. It is found that the proposed fully coupled THM model has a high accuracy with a relative error of around 1.2%. There is a large difference in the predicted bottomhole temperature (BHT) and thus the temperature in the reservoir between the models with and without considering fluid circulation in the wellbore. An assumption of constant temperature boundary condition may lead to overestimated or underestimated results depending on the selection of the assigned wellbore temperature. In the DSD case studied, the rock formation at the upper part of the reservoir (Z < 0.40) is continuously heated and the rock formation at the lower part (Z > 0.6) of the reservoir is continuously cooled during fluid circulation, which thus results in a complex heat transfer and thus mechanical behavior in the wellbore/reservoir system, especially near the wellbore. The bottomhole temperature (BHT) decreases by 38.9 K due to cold fluid circulation from 3.68 min to 25.68 days, which can lead to 14.59 MPa tensile stress that cannot be ignored for wellbore stability analysis. The proposed analytical model provides a useful tool to predict the mechanical behaviors such as the transient temperature, pressure, displacement and stresses in the wellbore/reservoir system during fluid circulation in DSD. It runs efficiently in terms of seconds per case study in a portable laptop computer and can also work a benchmark for other numerical methods. However, the fully coupled THM model and its analytical solution are based on several assumptions, such as the heat generated by the drill bit rotation is ignored and only the liquid phase is considered, which requires further investigation.

Determination of Reservoir Temperatures of Low-Enthalpy Geothermal Systems in the Sudetes (SW Poland) Using Multicomponent Geothermometers

Thermal waters from deep circulation systems are mixed with cold shallow system components during their ascent to drainage zones. In the current research, classic chemical geothermometers and geothermometric modeling using the GeoT app were employed to determine the temperatures of geothermal reservoirs in the Sudetic region. Moreover, models of primary deep components mixed with cold shallow circulation system components were used to determine their proportions, particularly water deposits. In the studied geothermal systems, the proportion of the cold component ranged from c. 46% to c. 75%. Classic cation thermometers (Na-K, Na-K-Ca) indicated a very wide temperature range and they proved rather unreliable. The reservoir temperatures estimated with silica thermometers ranged from 52 °C to 141 °C and they can be deemed more reliable. The temperatures obtained from modeling (54.5 ± 3–120 ± 4) were adopted as temperatures of waters pre-cooled conductively and then mixed with cold components. The temperatures of primary deep waters (74–225 °C) were adopted as geothermal system temperatures.

Study of ultrasound-guided percutaneous microwave ablation combined with portal vein embolization for rapid future liver remnant increase of planned hepatectomy.

To evaluate the efficacy of ultrasound-guided percutaneous microwave ablation (PMA) combined with portal vein embolization (PVE) for planned hepatectomy. We retrospectively reviewed data of 18 patients with multiple right liver tumors or hilar tumor of liver invades the surrounding tissue and insufficient future liver remnant (FLR) for hepatectomy from July 2015 to March 2017. Ultrasound-guided PMA was performed by using PMCT cold circulation microwave treatment apparatus. PVE was performed after PMA. The increase of FLR was evaluated by computed tomography (CT) 6-22 days after PVE. The proportion of FLR, increase in the amplitude of FLR, procedure-related complications, perioperative morbidity and mortality, and overall survival (OS) rates, the median survival time were analyzed. The median volume of FLR before PMA and PVE was 369.7ml (range: 239.4-493.1ml). After a median waiting period of 11.5 days (range: 6-22 days), the median volume of FLR was increased to 523.4ml (range: 355.4-833.3ml). The changes in FLR before and after PMA and PVE were statistically significant (p<0.001). No serious perioperative complications or mortality were found. After a median follow-up time of 51.0 months (range: 2-54 months), the 6-month, 1-year, 2-year, 3-year and 4-year survival rates were 88.9%, 72.2%, 44.4%, 33.3%, 22.2%, respectively, and the median survival time was 15.0 ± 7.1 months. PMA combined with PVE increases FLR rapidly, avoids touching malignant tumors, and produces fewer procedure-related complications. It appears safe and efficacious for planned hepatectomy.

The Alternating Change of Cold and Warm Extremes Over North Asia During Winter 2020/21: Effect of the Annual Cycle Anomaly

AbstractLarge‐scale cold and warm spells successively attacked North Asia (NA) and resulted in a subseasonal alternation of extreme surface air temperature (SAT) before and after 15 January 2021. Our results show the synergistic effect of annual cycle and intraseasonal oscillation component (AC and ISO) of SAT and circulation anomalies caused temperature extremes. Before 15 January 2021, an eastward‐propagating Rossby wave train strengthened the cold circulation regime with an enhanced Ural blocking high (UBH) and surface Siberian high (SH). Circulation anomalies of the negative ISO were superimposed on the counterpart of AC, which easily resulted in cold extremes via nonlinear interaction of meridional temperature gradient. After mid‐January 2021, however, weakened UBH and SH caused warm advection and spells over NA. This synergistic effect of AC and ISO anomalies in SAT accounted for most historical temperature extremes, implying that AC anomalies have important indications for subseasonal alternation of temperature extremes.

Analysis of Energy Management and Battery Sizing in an Off‐Grid Hybrid Solar Thermoelectric Generation System

Herein, the main aim is to analyze the idea of utilizing the thermal energy generated during the operation of a solar photovoltaic panel. The rise in temperature of the solar panels and the surrounding environment results in the reduction of the generated energy and ultimately the efficiency of solar panels. This thermal energy can be utilized to generate electrical energy by installing thermoelectric generators at the backside of the solar panel. The electrical energy generated through a thermoelectric generator depends on the temperature difference at its surface, which could be formed through any cooling mechanism such as natural air or cold water circulation. The electrical energy generated from the solar panels and thermoelectric generator can be integrated as a hybrid source, resulting in an enhancement of the overall efficiency of the system. On the other hand, designing a proper energy storage mechanism can enhance the efficiency and overall sustainability of the proposed idea. The results show that in doing so, not only does the solar panel temperature decrease resulting in the increase of its efficiency but utilizing the thermal losses by the hybrid solar thermoelectric generation system can enhance the energy generation up to 31.89% at a temperature difference of 34.4 °C.

Cryogenic secondary electron yield measurements on structural materials applied in particle accelerators

Multipacting phenomenon induced by large secondary electron yield (SEY) in cryogenic vacuum chambers and superconducting cavities is one of the significant issues in operating particle accelerators. Studying the characteristic and the factors influencing the secondary electron emission on cryogenic surfaces has become an inevitable task in the construction of accelerators. Here, custom cryogenic SEY measurement system with cold helium circulation facility has been established. Cryogenic SEY of structural materials (copper, aluminum, stainless steel, niobium and technical treated niobium) as a function of primary electron energy were evaluated. The experimental results show that SEY of materials at cryogenic temperature is lower than that at room temperature due to the adsorption of residual gases on the surfaces. Secondary electron emission can be effectively restrained by buffered chemical polishing treatment due to the removal of the contaminations and the build-up of graphitelike C–C bonds. After annealing treatments, the surface morphology of technical treated niobium has been modified, causing an increased roughness. Secondary electrons trapped by rough surface lower the SEY of technical treated niobium further. This paper is aimed to explore a rationale of cryogenic SEY characteristic of structural materials and evaluate the potential technical treatments for design and construction of Hefei advanced light facility (HALF).

Ensuring the Required Potable Water Temperature in Water Pipeline Inside Buildings

The paper deals with the requirements of the potable water cold temperature and water exchange in water piping system inside buildings. The contribution describes the main factors influencing the hygiene of potable water in terms of its temperature and a exchange in the pipeline. In buildings, the resulting water hygienic risks can be reduced using the right technical solution. The technical measures described in the paper are usage of the automatic water flushing system, design of the potable water cold circulation and cooling system and optimization of the water pipeline distribution system inside buildings.

A novel cyclical wellbore-fluid circulation strategy for extracting geothermal energy

Both analytical and numerical modeling methods have helped explore power generation by producing steam with the binary organic Rankine cycle or ORC. A steady-state fluid circulation rate becomes the norm in a closed-loop system in most studies, assuming a stable geothermal gradient. In this study, we explored the suitability of those assumptions, given that the geothermal gradient is a time-variant entity at a well's proximity. Furthermore, the near-wellbore formation cooling necessitates a variable-circulation rate for the cold surface fluid to ensure a stable, wellhead-fluid temperature.This article presents a new transient analytical modeling approach for geothermal energy extraction by invoking the cyclical fluid circulation rate to ensure a stable surface fluid temperature. This analytical model entails the reverse circulation of water down the annulus and up the tubing to the surface. Specifically, we introduce a cycle (a stepwise increasing circulation rate sequence, followed by the stepwise decreasing rate sequence) to retain a stable, wellhead-fluid temperature. Of course, this cycle gets repeated to manage transient heat transfer from cold fluid circulation and the wellbore formation.Reproduction of the undisturbed formation temperature from the temperature line-source solution at each step of the cycle provided the necessary proof of the proposed approach. Model validation entailed comparing the suggested analytical model results to demonstrate that multiple transient-rate steps yielded the same initial temperature, thereby reaffirming the stepwise increasing and decreasing rate sequence strategy. We also explored the model's application in diverse settings in a probabilistic frame. As expected, the geothermal gradient, vertical-well depth, and insulation strength became the most influential on the dependent variable, wellhead fluid temperature, among the various independent variables studied.

Numerical simulation of air flow and heat transfer in air refrigerated containers using clean energy technologies

Air refrigerated containers are important links and key equipment for air cold chain transportation. The refrigerated container cools the goods through the cold air circulation in the container to achieve the purpose of refrigeration. The key to the design of aviation refrigerators lies in the numerical simulation of the cold air flow and temperature distribution in the containers to determine the best air duct design and optimal air outlet arrangement. This article briefly analyzes the structure of the air refrigerated container, establishes the mathematical and physical models for numerical analysis, and then analyzes the two methods. At the same time, temperatures are tested in physical container with temperature measuring devices and conducts a comparative analysis with numerical simulation. The results show that the existing top on the basis of the air supply, assign a flow channel to each small tuyere and remove the small tuyere beside it. This situation is better for both flow and heat transfer. Temperatures in tests are similar with numerical simulation.

Research on Agricultural Product Cold Chain Logistics Management Based on Supply Chain Network Structure

he thesis first analyzes the supply chain network structure for the establishment of a new agricultural product supply chain system. This article is to construct a new agricultural product supply chain construction plan, establishes an innovative idea, the business process is urban fresh agricultural product e-commerce, and builds an urban standard distribution model A data-based cold chain integrated distribution model is proposed. This research is mainly to realize the joint operation and management of cold chain logistics and fresh products, and it is necessary to strengthen the coordination of demand-oriented agricultural industry organizations, the coordination of technological innovation of circulation enterprises, and the coordination of the implementation of innovative supply. As a result, the safety mechanism construction of the new agricultural product supply chain, including dynamic monitoring, detection modules and emergency handling systems, has guiding significance for the efficiency of agricultural cold chain logistics circulation.

Optimal operation strategies of multi-energy systems integrated with liquid air energy storage using information gap decision theory

In this paper, a framework of multi-energy system (MES) integrating with a liquid air energy storage (LAES) system was proposed. LAES, where liquid air works as an energy storage media, is a powerful and eco-friendly technology for storing renewable energy resources and reducing grid curtailment. Considering the characteristics of LAES (i.e. cold and heat circulation), the incorporation of LAES system into the Combined Cooling, Heating and Power system can achieve integrated use of energy and effectively save energy. Moreover, the prices of electricity will affect the overall cost of the MES. In other words, the decision-makers of the MES need to consider the uncertainty of electricity prices when making power dispatching decisions. To model the uncertainty of electricity prices, the information gap decision theory method was used to study power dispatching strategies of the MES. Three different strategies were proposed, including risk-neutral, risk-averse and risk-taker. In addition, demand response algorithms were used to study load transfer strategies. The results show that the demand responses of the three strategies are effective in terms of load transfer and cost saving. The total operation cost in the risk-neutral strategy with demand response can be 6.82% less than that without demand response; In the risk-taker strategy with demand response, the allowable grid electricity price is reduced by 25.24% when the opportunity cost drops by $8,000, and 23.32% without demand response. With additional robustness cost, the acceptable price change ratio using demand response is 21.91% in the risk-averse strategy, and 20.04% without demand response.

A novel internal cold circulation radiofrequency-assisted device for liver transection

Purpose To evaluate the safety and efficacy of a new internal cold circulation bipolar radiofrequency compared with Habib-4X bipolar radiofrequency device in the resection of liver tumors. Methods A total of 85 patients with hepatocellular carcinoma who received radiofrequency-assisted liver resection from February 2017 to January 2020 were retrospectively enrolled in our study, in which 45 patients received the new internal cold circulation bipolar radiofrequency (New-RF) and 40 patients received Habib-4X bipolar radiofrequency (Habib-4X). Primary outcome measures were the speed of liver transection, the width of coagulation tissue, hemorrhage volume, blood transfusion rate, and operation time. Results The baseline characteristics of patients in the New-RF and Habib-4X groups had no significant difference (p > 0.05). Compared to Habib-4X, the New-RF had a faster average speed of liver transection (4.81 ± 1.20 cm2/min vs 3.64 ± 1.08 cm2/min, p < 0.001), a narrower width of coagulation tissue (1.42 ± 0.23 cm2 vs 1.81 ± 0.20 cm2, p < 0.001), a less operation time (55.04 ± 16.12 min vs 64.02 ± 15.09 min, p = 0.010), a lower rate of needle path bleeding (13.3% vs 35.0%, p = 0.019), and a lower carbonization rate of electrode needle (22.2% vs 77.8%, p < 0.001). Hemorrhage during the transection (85.0 ml vs 105.0 ml, p = 0.438) and hemorrhage per square centimeter (3.28 ± 0.86 ml/cm2 vs 3.60 ± 1.12 ml/cm2, p = 0.141) in the New-RF group were smaller than those in Habib-4X group with no significant difference. Conclusion The new internal cold circulation bipolar radiofrequency was a safe and efficacious auxiliary device for liver resection with a faster speed of resection, lower carbonization rate of electrode needle, and more precise range of coagulation.

Development of thermosyphon controlled adsorptive natural gas storage system

Natural gas is considered a potentially available and ecologically preferable fuel, comparing to other liquid fossil fuels. Safe and sustainable energy storage device is one of the bases for changing the current energy systems. The system is to use tank packed with porous solid that can selectively adsorb methane at a gas pressure of 3.5–6 MPa. This low storage pressure in the gas tank reduces both the cost of compression and that of the storage tank, and poses less of a safety hazard than higher pressures used for compressed natural gas. The focus was the study of the effect exerted by the hybrid cooling technology and sorbent characteristics on the gas reserve. For dual-fuel internal combustion engines, a modular adsorbed natural gas (ANG) tank with an active and passive thermal control system was proposed. Dynamic charging is analyzed using a numerical model of the real properties of the sorbent and reservoir design. Novel thermosyphons with annular channels in long horizontal evaporators and a cold gas circulation loop made it possible to stimulate gas adsorption and avoid the rise of temperature in the sorbent bed during filling the tank with a gas at gas stations. They are capable of transporting energy for a distance of some meters which is difficult to be realized by horizontally disposed conventional thermosyphons and heat pipes.

Discussion on dehydration technology of coal mine low-concentration gas reciprocating internal combustion engine

Low concentration gas reciprocating internal combustion engine power generation in coal mine is one of the main ways of gas utilization. This paper aims at the technical problem of low concentration gas power generation efficiency caused by large amount of atomized liquid water carried by gas in low concentration gas pipeline. Based on the analysis of the source of low concentration gas liquid water, this paper discusses in detail research progress of dehydration technology for low concentration gas reciprocating internal combustion engine power generation, and key discusses the mechanical separation method, electric refrigeration method, electric refrigeration combined with cold air circulation method and flue gas residual heat variable temperature method for gas dehydration of low concentration gas power generation.

Heat production from lab-scale enhanced geothermal systems in granite and gabbro

Lab-scale cold water circulation test results and analysis are presented as a proxy for field-scale heat mining in enhanced/engineered geothermal systems. The cold water circulation tests were conducted in hydraulically stimulated igneous rock blocks heated to a uniform temperature. The test blocks had a five-spot system with one injection well at the center and four producers drilled about 9 cm away from it. Two kinds of igneous rocks (granite and gabbro) with different permeability were tested. Due to the heterogeneity of the rock and the notch at the injection well, different fracture geometries with different number of producers connected by the hydraulic fracture were obtained. The circulation tests illustrate for the first time a number of interesting phenomena in a laboratory setting. The great potential of geothermal energy has been demonstrated by nearly 50W of power produced by the cold water flowing through a hydraulic fracture in a mini-EGS reservoir, yielding a good heat extraction percentage of 6.24%~7.85% after 2000 ml of cold water injection. Also, the cooling effect on the injection pressure and thus the fracture aperture has been clearly observed in the experiments i.e., with continued cold water injection the pressure drops, indicating fracture aperture increase due to thermal stress. In addition, reservoir growth during circulation has been observed based on the AE record and production data. Production well competition has also been observed when multiple producers were connected to the injection well by the induced hydraulic fracture, emphasizing the necessity of proper field management to maximize heat production. The test result indicates that a more “complex” flow path enhances heat production, and early thermal breakthrough and undesirable fracture propagation can be avoided by close monitoring of AE, pressure, and production responses.

Effects of Under-Resolved Convective Dynamics on the Evolution of a Squall Line

Abstract Simulations of a squall line observed on 20 May 2011 during the Midlatitude Continental Convective Clouds Experiment (MC3E) using 750- and 250-m horizontal grid spacing are performed. The higher-resolution simulation has less upshear-tilted deep convection and a more elevated rear inflow jet than the coarser-resolution simulation in better agreement with radar observations. A stronger cold pool eventually develops in the 250-m run; however, the more elevated rear inflow counteracts the cold pool circulation to produce more upright convective cores relative to the 750-m run. The differing structure in the 750-m run produces excessive midlevel front-to-rear detrainment, reinforcing excessive latent cooling and rear inflow descent at the rear of the stratiform region in a positive feedback. The contrasting mesoscale circulations are connected to early stage deep convective draft differences in the two simulations. Convective downdraft condensate mass, latent cooling, and downward motion all increase with downdraft area similarly in both simulations. However, the 750-m run has a relatively greater number of wide and fewer narrow downdrafts than the 250-m run averaged to the same 750-m grid, a consequence of downdrafts being under-resolved in the 750-m run. Under-resolved downdrafts in the 750-m run are associated with under-resolved updrafts and transport mid–upper-level zonal momentum downward to low levels too efficiently in the early stage deep convection. These results imply that under-resolved convective drafts in simulations may vertically transport air too efficiently and too far vertically, potentially biasing buoyancy and momentum distributions that impact mesoscale convective system evolution.

Design of fresh food sensory perceptual system for cold chain logistics

According to the present stage low-level information of China's cold chain preservation, designed a kind of fresh food sensory perceptual system for cold chain logistics based on Internet of things. This system highly integrated applied many technologies such as the Internet of things technology, forecasting technology for fruits and vegetables preservation period, RFID and Planar bar code technology, big data and cloud computing technology and so on.Designed as a four-layer structure including sensing layer, network layer, control layer and user layer. The system can implement the real-time temperature and humidity environment parameters monitoring and early warning of the whole cold chain logistics for fresh agricultural products from picking, storage, transportation and processing link. It greatly improved the information level of cold chain circulation in our country and has a strong marketing value.