Vapor Injection Research Articles

Thermodynamic analyses of a solar assisted ejector enhanced vapor injection cycle with subcooler for heat pump dryer application

This paper presents a solar assisted ejector enhanced vapor injection cycle with a subcooler (SE-SVIC) for heat pump dryer applications. The proposed cycle improves the heat absorption per unit of mass in the evaporator because the lower subcooler outlet temperature can be obtained with the pressure lift ability of the ejector. The cycle performances of SE-SVIC are evaluated and compared with those of the basic subcooler vapor injection cycle (SVIC) and the ejector enhanced subcooler vapor injection cycle (E-SVIC). The results show that the COPh of SE-SVIC is improved by 23.8 % and 19.0 % compared with SVIC and E-SVIC under the typical operating condition, respectively. The heating performance of SE-SVIC is largely dependent on the solar energy input ratio. Overall, the input of solar energy can achieve significant improvement in the heating capacity of SE-SVIC if there is sufficient solar radiation available for the solar collector. Further, the largest exergy destruction of SE-SVIC occurs in the solar collector. As the increase of the solar radiation intensity, the exergy input increases more obviously than the exergy destruction, and thus the exergy efficiency of SE-SVIC is increased. The theoretical results show the energy saving potential of the proposed cycle and its application perspective in the heat pump dryer.

Experimental investigation on improving defrosting performance of air source heat pump through vapor injection

During the defrosting process in cold regions, the air source heat pump with vapor injection encounters some problems, e.g. long defrosting time and low defrosting efficiency. To solve these problems, a new defrosting strategy through injecting medium-pressure vapor refrigerant into compressor during defrosting process was proposed based on its special structure. Five groups of experiments having different openings of injection electronic expansion valve were designed and conducted to investigate the effect of this defrosting strategy. Results indicate that an optimal opening of injection electronic expansion valve exists during defrosting process with vapor injection. For the experimental air source heat pump, it is 50%. At the opening of less than 50%, the experimental unit can run safely and defrosting performance improves gradually with the opening increase. When the opening increases to greater than 50%, the defrosting process is unsteady. At the optimal opening of injection electronic expansion valve, the defrosting time and power consumption are respectively decreased by 20.61% and 17.98%, while the defrosting efficiency is improved by 6.22%.

A study of a low pressure ratio vapor injection scroll compressor for electric vehicles under low ambient conditions

Vapor injection technology is a promising method to improve the performance of heat pump systems on electric vehicles. In this work, an experimental study on a low pressure ratio vapor injection scroll compressor was carried out under low ambient temperature conditions. Comparative experiments were conducted for various injection pressures, compressor speeds, and evaporation temperatures. The typical flow and heat transfer characteristics were obtained and analyzed, especially the compressor volumetric efficiency and compressor efficiency. The results showed that the heating performance was improved and discharge temperature was reduced with the increasing injection pressure at a higher compressor speed and a lower evaporation temperature. The volumetric efficiency and compressor efficiency both decreased with the increasing injection pressure. The maximum heating capacity could increase by 16% and the maximum discharge temperature reduction would reach 8 °C for the vapor injection process compared with non-injection process under the evaporation temperature of -22 °C. Furthermore, a semi-empirical model with correlations of volumetric efficiency and compressor efficiency was developed. The results were validated and showed a reasonable agreement with experimental results.

Control of Heterogeneous Nucleation in Carbon Steel by Magnesium Vapor Injection during Continuous Casting

Control of Heterogeneous Nucleation in Carbon Steel by Magnesium Vapor Injection during Continuous Casting

Performance investigation and design optimization of a vapor injection rotary compressor without check valve in injection path

• The reason for the backflow of injection compressor is analyzed. • The optimal start and end of injection rotation angles are proposed. • The optimal design of the injection port increases the heating capacity by 22–45%. • The optimal design of the injection port increases the COP by 3.06–5.15%. • The operating strategy is optimized based on the CFD results. In recent years, low-temperature air source heat pumps using vapor refrigerant injection technique, which can effectively improve the performance and heating capacity of the rotary compressor heat pump systems in cold regions, have become more and more widely used. The injection rotary compressor without a check valve in the injection path has a great manufacturing advantage compared to that with a check valve. Improper position of the injection port will cause serious backflow during compression, which will greatly affect the performance of the heat pump. In order to study and correct the backflow in the injection process of the compressor, this paper analyzes the refrigerant flow characteristics of the compressor with a circular injection port without a check valve based on experiments and computational fluid dynamics. Through the analysis of the cause of backflow, the optimal position of the injection port is proposed, which has effectively solved the problem of refrigerant backflow caused by the injection. In addition, the operating strategy is optimized based on the results of computational fluid dynamics. The simulation results indicate that at low ambient temperatures, the optimal design of the injection port structure has increased the heating capacity 21.75%–45.3% over the traditional compressor without injection, and the coefficient of performance for heating also has been increased by 3.06%–5.15%.

Theoretical and Experimental Study on Rotary Compressor with Double Vapor Injection and Its System

This paper takes three kinds of double vapor injection compression cycle as the research object, that is, the two-stage compression cycle with double vapor injection on low-pressure cylinder and intermediate of two cylinders (Cycle A), the two-stage compression cycle with double vapor injection on high-pressure cylinder and intermediate of two cylinders (Cycle B), and the three-stage compression cycle with double vapor injection (Cycle C). According to the law of conservation of mass and energy, the thermodynamic analysis model of each cycle was established, and the influence of saturation temperature of double vapor injection on the performance of each cycle was analyzed. The theoretical analysis results indicated that the refrigeration capacity of cycle A, cycle B and cycle C increase by 12.5%, 3.5% and 4.6%, respectively, and COP of that increase by 3.09%, 2.23% and 3.22%, respectively, compared with that of single stage compression cycle. Based on cycle A, a single-machine two-stage rotary compressor with double vapor injection and its heat pump air conditioning are made. The experimental results showed that, the heating capacity of cycle A can increase by 14.6% when the heating COP is equivalent, and the heating COP can increase by 4.4% when the heating capacity is equivalent, compared with the two-stage compression cycle with single vapor injection, under the –15°C ambient temperature heating condition.

MP09-07 SIX- AND TWELVE-MONTH OUTCOMES OF A PROSPECTIVE TRIAL OF WATER VAPOR THERMAL THERAPY FOR TREATMENT OF LOWER URINARY TRACT SYMPTOMS DUE TO BENIGN PROSTATIC HYPERPLASIA IN SUBJECTS WITH LARGE PROSTATES

You have accessJournal of UrologyBenign Prostatic Hyperplasia: Surgical Therapy & New Technology II (MP09)1 Sep 2021MP09-07 SIX- AND TWELVE-MONTH OUTCOMES OF A PROSPECTIVE TRIAL OF WATER VAPOR THERMAL THERAPY FOR TREATMENT OF LOWER URINARY TRACT SYMPTOMS DUE TO BENIGN PROSTATIC HYPERPLASIA IN SUBJECTS WITH LARGE PROSTATES Henry Woo, Richard Levin, Christopher Cantrill, Shaw Zhou, Donald Neff, Mark Sutton, James Bailen, and Michael Darson Henry WooHenry Woo More articles by this author , Richard LevinRichard Levin More articles by this author , Christopher CantrillChristopher Cantrill More articles by this author , Shaw ZhouShaw Zhou More articles by this author , Donald NeffDonald Neff More articles by this author , Mark SuttonMark Sutton More articles by this author , James BailenJames Bailen More articles by this author , and Michael DarsonMichael Darson More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000001982.07AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: We report the twelve-month results of a multicenter, single arm trial of water vapor thermal therapy in men with symptomatic lower urinary tract symptoms due to benign prostatic hyperplasia (BPH) in subjects with prostate volume >80 cm3 and ≤150 cm3. METHODS: 47 subjects >50 years old with International Prostate Symptom Score (IPSS) ≥13, maximum flow rate (Qmax) 5-12 ml/s with minimum voided volume of >125 mL and prostate volume >80 cm3 and ≤150 cm3 were treated with Rezūm Water Vapour Thermotherapy System. Treatment involved injection of water vapor into lateral lobes and, where necessary, central zone and median lobe. The primary efficacy endpoint was the proportion of subjects with an IPSS improvement ≥30% post-treatment compared to baseline at 6 months, and the secondary endpoint was absolute IPSS improvement at 6-months greater than 6 points. The primary safety endpoint was the proportion of subjects with one or more safety composite events within 6 months post-procedure, defined as perforation of the rectum or genitourinary tract, fistula formation between the rectum and urethra, permanent damage to the bladder, trigone or ureteral orifices requiring intervention, or Grade 2 hydronephrosis. Ancillary endpoints included change in IPSS-quality of life (QoL), BPHII, Qmax and post-void residual (PVR) at 6 and 12 months. RESULTS: At 6 months post-procedure, the responder rate was 83% (39/47) with a 95% confidence interval (CI) lower bound of 69.2%. There was a significant improvement in absolute IPSS with mean improvement at 6 months of 11.9 ± 7.5 points (95% CI, 9.7 to 14.1); Baseline was 20.6 ± 5.2 points, and 6 months was 8.7 ± 7.4 points. No composite safety events occurred within 6 months post-procedure (95% CI, 0.0% to 7.5%). Qmax was higher than baseline at 6- and 12-months post-procedure (table 1) with a mean improvement at 12 months of 7.1 ± 7.0mL/sec (95% CI, 4.9 to 9.3). There was a reduction from baseline of IPSS-QoL, BPHII and PVR at 6 months which was durable through 12 months (table 1). CONCLUSIONS: These results provide supportive scientific evidence of the safety, effectiveness, and clinical benefit of the Rezūm System to successfully treat the symptoms of BPH in men with larger prostates >80 cm3 and ≤150 cm3. Source of Funding: Boston Scientific © 2021 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 206Issue Supplement 3September 2021Page: e161-e162 Advertisement Copyright & Permissions© 2021 by American Urological Association Education and Research, Inc.MetricsAuthor Information Henry Woo More articles by this author Richard Levin More articles by this author Christopher Cantrill More articles by this author Shaw Zhou More articles by this author Donald Neff More articles by this author Mark Sutton More articles by this author James Bailen More articles by this author Michael Darson More articles by this author Expand All Advertisement Loading ...

Thermodynamic analysis and optimization of a vapor injection organic Rankine cycle system for low-grade heat recovery

The organic Rankine cycle (ORC) system has been widely used in waste heat recovery and geothermal utilization, but the system efficiency is limited due to the large exergy loss in the evaporation process. To improve the performance of ORC systems, in this paper, a vapor injection organic Rankine cycle (VIORC) system using positive-displacement expanders was proposed. The thermodynamic model of the proposed system was developed in views of energy and exergy. The effects of system operation parameters on system performance were investigated, and the system was optimized under different waste heat temperatures. Furthermore, the optimized systems were compared with basic ORC (BORC) systems. Results showed that compared with the BORC system, the proposed system increased the net output power by 3-8% and the exergy efficiency by 0.8-3.2% under the heat source temperature of 90-150 °C. The exergy loss analysis further showed that the reduction of the exergy loss in the evaporation process was the main contribution to the efficiency improvement of the proposed system.

Activity of Ag/CeZrO2, Ag+K/CeZrO2, and Ag-Au+K/CeZrO2 Systems for Lean Burn Exhaust Clean-Up

Herein, the activity of Ag and bimetallic Au-Ag catalysts, supported over Ce0.85Zr0.15O2 (CZ), was investigated in a complex stream, whose components included CO, C3H8, NO, O2, and, optionally, an injection of water vapor. In such a stream, three of the possible reactions that can occur are CO oxidation, propane combustion, and NO oxidation. The aim of these studies was to explore whether silver, due to its strong affinity to oxygen, will counteract the stabilization of oxygen by potassium. The effect of the presence of potassium ions on the activity of the monometallic silver catalysts is beneficial in the complex stream without water vapor in all three studied reactions, although it is negligible in the model CO stream. It has been shown that water vapor strongly suppresses the activity of the Ag+K/CZ catalyst, much more so than that of the Ag/CZ catalyst. The second purpose of the work was to determine whether the negative effect of potassium ions on the activity of nanogold catalyst can be countered by the addition of silver. Studies in a model stream for CO oxidation have shown that, for a catalyst preloaded with gold, the effect of potassium is nulled by silver, and the activity of AuAg + 0.15 at%K/CZ and AuAg + 0.30 at%K/CZ is the same as that of the monometallic Au catalyst. Conversely, when the reaction is carried out in a complex stream, containing CO, C3H8, NO, O2, and water vapor, the presence of water vapor leads to higher CO conversion as well as increased NO2 formation and slightly suppresses the C3H8 combustion.

Review of Mechanical Vapour Compression Refrigeration System Part 2: Performance Challenge

Reducing energy consumption and providing high performance for a vapour compression refrigeration system are big challenges that need more attention and investigation. This paper provides an extensive review of experimental and theoretical studies to present the vapour compression refrigeration system and its modifications that can be used to improve system’s performance and reduce its energy consumption. This paper also presents the challenges that can be considered as a gab of research for the future works and investigations. Cooling capacity, refrigerant effect, energy consumption can be improved by using vapour injection technique, natural working fluid, and heat exchanger. Based on the outcome of this paper, vapour injection technique using natural refrigerant such as water can provide ultimate friendly refrigeration system. Future vision for the vapour compression refrigeration system and its new design technique using Computational Fluid Dynamic (CFD) is also considered and presented.

Effect of Water Vapor Injection on the Performance and Emissions Characteristics of a Spark-Ignition Engine

The exhaust emissions from Internal Combustion Engines (ICE) are currently one of the main sources of air pollution. This research presented a method for improving the exhaust gases and the performance of a Spark-Ignition (SI) engine using a water vapor injection system and a Non-Thermal Plasma (NTP) system. These two systems were installed on the intake manifold to investigate their effects on the engine’s performance and the characteristics of exhaust emission using different air/fuel (A/F) ratios and engine speeds. The temperatures of the injected water were adjusted to 5 and 25 °C, using a thermoelectric cooler (TEC) temperature control device. The total hydrocarbons (HC), nitrogen oxide (NOx), and engine torque were measured at different A/F ratios and engine speeds. The results indicated that the adaptation of the water vapor injection system and NTP system increased the content of the combustibles and combustion-supporting substances while achieving better emissions and torque. According to the test results, while the engine torque under 25 °C water+NTP was raised to 7.29%, the HC under 25 °C water+NTP and the NOx under 25 °C water were reduced to 16.31% and 11.88%, respectively. In conclusion, the water vapor injection and the NTP systems installed on the intake manifold could significantly reduce air pollution and improve engine performance for a more sustainable environment.

Ten megawatt scale vapor compression heat pump for low temperature waste heat recovery: Onsite application research

In order to limit global warming of 1.5 °C before 2050, the heat pump with waste heat recovery has been acknowledged as an effective technical solution. In this paper, a new kind of centrifugal heat pump system is applied to recover the waste heat from a steel plant for district heating. Two centrifugal compressors with vapor injection and two-cycle parallel connected system configuration are adopted to achieve higher energy efficiency and larger heating capacity. From simulation, the COP is expected to be more than 6 with a temperature rise of above 30 °C. To validate the calculation results, a 10 MW scale (9.5 MW) centrifugal heat pump was installed and tested in Angang Lingshan steel plant of China. With the waste water inlet temperature of 32.5 °C and hot water outlet temperature of 62.5 °C, the tested COP and heating capacity were 6.67 and 9.67 MW, respectively. The heating capacity of the system was greater than the heating load under severe conditions. Environmental and economic analyses of the waste heat recovery system are presented, showing advantages compared to the conventional heating methods. The PER of megawatt compression heat pump is as high as 2.53 and the payback period of this waste heat recovery system is 1.66 years.

Plasma mass separation in configuration with potential well

The details of the charged particle separation by mass in the configuration with axial magnetic and radial electric fields are studied. The radial electric field, oriented to the discharge axis, is induced in a background reflex discharge with a hot cathode (−550 V, 8–14 A). The plasma source is based on a hot cathode arc discharge with independent metal vapor injection (18–21 V, 30 A) was situated at 18 cm from the axis. It was shown that the separated Ag + Pb mixture is transported across the magnetic field under the background discharge electric field. Effective separation is possible in such a system, while the separation coefficient increases from 4.9 to 6.2–8.4 when the mixture injection point is moved away from the background discharge axis from 18 to 23 cm. The effect of mixture injection on the plasma potential distribution is examined. It was shown that the presence of a plasma source of separated substances can cause a local (1–2 cm) distortion of the background plasma potential profile. Such distortion, as well as fluctuations of the background plasma potential, can significantly affect the width of the deposited spots of separated substances.

Experimental investigation and comparison on heating performance characteristics of two transcritical CO2 heat pump systems

An experimental investigation and comparison of the heating performance of the transcritical CO2 single-stage and vapor injection cycles were conducted. The effects of operating parameters on the heating performance of the two cycles were investigated. The experimental results showed that the heating capacity of the vapor injection cycle was 7.0% higher and the discharge temperature of the refrigerant was 7.7–11.8 ℃ lower than that of the single-stage cycle under the same condition. Besides, both the compressor input power and heating capacity were increased with the increasing temperature of the glycol aqueous solution. However, the growth rate of heating capacity was greater than that of the compressor input power. Therefore, the coefficient of performance of the vapor injection cycle was 4.4% greater than that of the single-stage cycle. So the vapor injection cycle has a wider range of applications in cold conditions. When the vapor injection pressure increased, the coefficient of performance of the vapor injection cycle increased then decreased, so there was a peak of the coefficient of performance. Therefore, a new correlation of the optimal vapor injection pressure was proposed. The new correlation has a significant meaning for designing a transcritical CO2 vapor injection cycle.

Energy, Exergy, and Environmental (3E) Analysis of Hydrocarbons as Low GWP Alternatives to R134a in Vapor Compression Refrigeration Configurations

The phase-down of hydrofluorocarbons and substitution with low global warming potential values are consequences of the awareness about the environmental impacts of greenhouse gases. This theoretical study evaluated the energy and exergy performances and the environmental impact of three vapor compression system configurations operating with the hydrocarbons R290, R600a, and R1270 as alternatives to R134a. The refrigeration cycle configurations investigated in this study include a single-stage cycle, a cycle equipped with an internal heat exchanger, and a two-stage cycle with vapor injection. According to the results, the alternative hydrocarbon refrigerants could provide comparable system performance to R134a. The analysis results also revealed that using an internal heat exchanger or a flash tank vapor injection could improve the system’s efficiency while decreasing the heating capacity. The most efficient configuration was the two-stage refrigeration cycle with vapor injection, as revealed by the exergy analysis. The environmental impact analysis indicated that the utilization of environmentally-friendly refrigerants and improving the refrigeration system’s efficiency could mitigate equivalent CO2 emissions significantly. The utilization of hydrocarbons reduced the carbon footprint by 50%, while a 1% to 8% reduction could be achieved using the internal heat exchanger and flash tank vapor injection.

Performance analysis of an ejector-boosted solar-assisted flash tank vapor injection cycle for ASHP applications

A novel ejector-boosted solar-assisted flash tank vapor injection cycle (ES-FVIC) is proposed for air source heat pump (ASHP) applications. The heating performances of the ES-FVIC and the conventional flash tank vapor injection cycle (FVIC) are analyzed by employing the developed mathematical model. Compared with FVIC, the simulation results shows ES-FVIC using R134a has 21.4–29.0% improvements in heating COP and 82.1–108.3% improvements in volumetric heating capacity at the given evaporating temperature range (−20 to +5 °C) when the ejector’s pressure lift ratio is set as 1.5. The performance improvement amount of the new cycle is primarily determined by the solar energy input ratio. The system can accommodate the changes of solar energy input ratio within a wide range (from 0.3 to 2.0) by adjusting the ejector pressure lift ratio. The system can be switched to the conventional FVIC when solar energy input is too less to support the proper operation. The heating performances of using three low-GWP substitutes (R32, R290 and R1234yf) in ES-FVIC and the comparison with R134a are also presented. The ES-FVIC has shown its potential in advanced solar energy utilization by applying the ejector to improve the performance of the FVIC and enlarge its application in ASHP.

Indirect mechanical heat pump assisted humidification‐dehumidification desalination systems

In this study, four new indirect heat pump assisted mechanical vapor compression humidification-dehumidification (HDH) systems are proposed and their superiorities over the reference system are demonstrated from thermodynamics and thermoeconomics viewpoints. The proposed models are configured based on an HDH unit and a simple cascade heat pump, an HDH unit and a heat pump with an ejector, an HDH unit and a cascade heat pump with an ejector, and an HDH unit and a vapor injection heat pump. Although employing a heat pump with cascade and ejector configurations improved gain-output-ratio (GOR) and specific power consumption (SPC) values in comparison with the base system, the performance metrics of such layouts are still inferior to those of the HDH unit coupled with the vapor injection heat pump. It is found that the desalination unit with vapor injection mechanism has the highest GOR and the lowest SPC values of 9.22 and 71.29 kWh/m3, respectively, under constant electrical power of 31.26 kW. Overall, proposal of the cascade heat pump, heat pump with an ejector, cascade heat pump with an ejector, and a vapor injection heat pump instead of the conventional heat pump improved GOR by 4.83%, 10.03%, 11.52%, and 14.25%, respectively. Meantime, the SPC of the HDH unit coupled with a simple heat pump decreased by 4.6%, 9.1%, 10.26%, and 12.46% when a cascade heat pump, a heat pump with an ejector, a cascade heat pump with an ejector, and a vapor injection heat pump were used instead of the conventional heat pump, respectively. Also, it is found that a maximum improvement of 14.13% can be achieved in exergy efficiency with a cost penalty of only 1.59 $/m3. Also, it was found that with the use of a simple cascade heat pump instead of the simple heat pump, the exergy efficiency can be enhanced by 4.9%, while the unit cost of the distilled water (UCDW) was degraded by 51.32%. Likewise, the HDH unit coupled with the cascade heat pump with an ejector was resulted in high UCDW compared to the base system, while its exergy efficiency was not enhanced so significantly. Variation of exergy efficiency versus the intermediate temperature had a maximum value of 1.93% (for the HDH unit coupled with a simple cascade heat pump) and 2.05% (for the HDH unit coupled with a cascade heat pump with an ejector) at Tint = 315 K. Moreover, it was found that the UCDW can be decreased with the rise of the intermediate temperature and cascade heat exchanger temperature difference as the fresh water cost rate decreases as a result, while the exergy efficiency can be increased with the rise of the cascade heat exchanger temperature difference.

On Optimization of the Metal Ion Production by Electron Cyclotron Resonance Ion Sources

The three-dimensional NAM-ECRIS model is applied for studying the metal ion production in the DECRIS-PM Electron Cyclotron Resonance Ion Source. Experimentally measured extracted ion currents are accurately reproduced with the model. Parameters of the injection of metal vapors into the source are optimized. It is found that the axial injection of the highly directional fluxes allows increasing the extracted ion currents of the highly charged calcium ions by factor of 1.5. The reason for the gain in the currents is formation of internal barrier for the ions inside the plasma, which increase the ion extraction and production efficiency. Benefits of injecting the singly-charged calcium ions instead of atoms are discussed.

Screening and confirmation of 244 pesticide residues in chilli by gas chromatography-quadrupole time-of-flight mass spectrometry

建立了辣椒中244种农药残留的QuEChERS前处理结合气相色谱-四极杆/飞行时间质谱(GC-Q-TOF/MS)快速筛查确证方法。鲜辣椒和干辣椒样品分别采用经-20 ℃冷冻的乙腈和1%(v/v)乙酸化乙腈提取,经盐析分层、分散固相萃取净化和浓缩后加入内标并复溶,HP-5MS UI色谱柱(30 m×0.25 mm×0.25 μm)分离,程序升温不分流进样,GC-Q-TOF/MS全扫描模式采集,内标法定量。比较了分析保护剂(AP)和基质匹配校准法对基质效应的补偿效果,最终选择采用基质匹配校准法来补偿基质效应并进行样品中农药残留的校准定量。设置定性筛查中的保留时间最大偏差为±0.25 min,精确质量偏差阈值为±20×10 -6。对鲜辣椒中244种农药残留和干辣椒中222种农药残留进行了定量方法验证,实验结果表明,采用建立的数据库和分析方法可以对辣椒进行农药残留的高通量筛查和定量分析。在空白辣椒样品中添加不同水平的目标化合物,以信噪比S/N≥10对应的添加水平作为定量限(LOQ)。鲜辣椒中最大残留限量(MRL)≤0.05 mg/kg的44种农药在鲜辣椒中LOQ≤0.010 mg/kg,线性范围在0.01~1.00 mg/L,在1倍和2.5倍LOQ添加水平下,回收率在60%~120%的农药种类占比分别为88.64%和100%;鲜辣椒中暂无MRL规定或MRL>0.05 mg/kg的200种农药在鲜辣椒中LOQ≤0.025 mg/kg,线性范围在0.05~1.00 mg/L,在1倍、2倍和10倍LOQ添加水平下,回收率在60%~120%的农药种类占比分别为49.50%、87.00%和89.50%; 244种农药的线性相关系数(r 2)均大于0.99。222种农药在干辣椒中LOQ≤0.15 mg/kg,线性范围在0.04~1.00 mg/L, r 2≥0.99的比例为95.46%,在1倍、2倍和10倍LOQ添加水平下,回收率在60%~120%占比分别为72.52%、73.42%和81.53%。应用建立的筛查确证方法对市售的12份鲜辣椒样品和14份干辣椒样品进行农药残留筛查分析,从9份鲜辣椒样品和3份干辣椒样品中筛查出8种农药化合物,经人工鉴定均为阳性,定量结果显示,8种农药化合物均未超过其在GB 2763-2019《食品安全国家标准食品中农药最大残留限量》所规定的MRL。方法快速、简单、高效、可靠,适用于鲜辣椒及干辣椒中多种农药残留的筛查分析。

A novel configuration for low-grade heat-driven desalination based on cascade MED

A novel MED-based desalination system for low-grade heat sources with a temperature between 65 °C and 90 °C has been proposed. Low-grade heat-driven desalination systems are of the most important methods for increasing energy efficiency and assisting the environment along with alleviating the water scarcity problem. The new proposed system is known as cascade multi-effect distillation (CMED). It is designed based on multi-step heat extraction from the heat source fluid (HSF). Multi-step heat absorption helps to form two arrays of MED effects and to utilize two boosters to achieve better performance. The advantage of this system is less complexity (for example, lower vapor injection), and improved performance along with reduced electricity consumption in comparison with the most recent MED-based configurations, including flash boosted MED (FB-MED) and distributed boosted MED (DBMED). The results show that the CMED’s production rate is increased on average by 15.5% compared to FB-MED, and up to 7.3% relative to DBMED. The normalized pumping power consumption (NPPC) is dropped by 14.5% and 11.5% on average compared to FB-MED and DBMED, respectively. Also, the specific capital cost is reduced by about 1.15% and 0.80% on average.