Development and Test of a Novel Electronic Radiator Thermostat with a Return Temperature Limiting Function

Automated hydronic balancing in space heating systems is crucial for the fourth-generation district heating transition. The current manual balancing requires labor- and time-consuming activities. This article presents the field results of an innovative electronic radiator thermostat tested on two Danish multi-family buildings. The prototypes had an additional return temperature sensor on each radiator and an algorithm was used to accurately control valve opening to ensure automated hydronic balancing. The results highlighted that the new thermostat performed as expected and helped secure the cooling of district heating temperatures —defined as the difference between supply and return temperature—4–12 °C higher during the test compared to results obtained in 2020, when the prototypes were replaced with state-of-the-art thermostats in the first building. The measurements from the other building illustrated how only two uncontrolled radiators out of 175 could contaminate the overall return temperature. The remote connection of the thermostats helped pinpoint the faults in the heating system, although the end-users were not experiencing any discomfort, and secure, after fixing the problems, a return temperature of 35 °C. Future designs may consider integrating a safety functionality to close the valve or limit the flow in case of damage or malfunction to avoid a few radiators compromising the low-temperature operation of an entire building before the cause of the problem has been identified.

Pengaruh variasi campuran bahan bakar pertamax dan bioetanol 99,9% terhadap torsi mesin bensin 4 langkah Tecquipment TD201

Bioethanol is ethanol made from plants such as cassava, sugarcane, sago, which are processed through hydrolysis, fermentation, distillation and dehydration processes. Lampung Province is one of the largest producers of cassava in Indonesia, with the total productivity of 5,451,312 tons in 2017, and 6,683,758 tons in 2018 or there was an increase of 22,61% compared to 2017. From this data, it is possible to produce bioethanol, where every 1 kg of cassava can produce 0,106 liters of bioethanol. This is what underlies this research to investigate the effect of blending bioethanol of 99% with pertamax and bioethanol on the engine torque. Blending bioethanol of 99% can homogeusly mix. The engine used in this study is a Kohler gasoline engine equipped with a VDAS (Versatile Data Accession System) instrument unit in determining the parameters of engine performance. The blending of bioethanol of 99% as big as 14% (E14) gave the highest value of torque at 1 rotation of dynamometer valve opening and engine speed of 2000 rpm.

Three-year results of Ozaki surgery in patients aged ≥65 years: a multicentre study

<p><strong>Background.</strong> Currently, aortic valve stenosis is the most common disease of the native valve, which affects 5% of the elderly population. In symptomatic patients, aortic valve replacement is the ‘gold standard’. For patients aged ≥65 years, the use of biological prostheses is recommended. The Ozaki operation is an alternative to bioprostheses.</p><p><strong>Aim.</strong> The aim of this study was to evaluate the immediate and 3-year results of Ozaki surgery in patients aged ≥65 years.</p><p><strong>Methods.</strong> This was a prospective multicentre study conducted on 107 patients aged ≥65 years, who underwent the Ozaki procedure at three centres during 2016–2019. There were 46 (43%) men. The median age of the patients was 69 [67–74] years. Severe aortic stenosis was the major cause of aortic valve dysfunction (106 patients [99.1%]). Chronic heart failure III–IV functional class according to NYHA was diagnosed in 47 (43.9%) patients. The following complications were also registered: atrial fibrillation in 30 (28%) patients, a history of diabetes mellitus in 16 (15%) patients, chronic obstructive pulmonary disease in 14 (13.1%) patients and coronary artery disease in 42 (39.2%) patients. Bicuspid aortic valve was detected in 36 (34.6%) patients. There were 72 (67.2%) patients with a small annulus (≤21 mm) and 59 (55.14%) patients with a left ventricular ejection fraction of 64%. The median follow-up period was 23 [18–33] months. This study included all patients who underwent Ozaki surgery from 2016 to 2019.</p><p><strong>Results.</strong> No patient had any conversions. A total of 45 (42.1%) patients underwent combined interventions. The operation duration was 240 [214–300] min, cardiopulmonary bypass duration was 104 [93–120] min and aortic cross-clamp duration was 82 [72–95] min. The rate of hospital mortality was 1.9%, and the incidence rates of acute renal failure requiring haemodialysis, stroke, pacemaker implantation, sepsis and reoperation for bleeding were 1.9%, 0.9%, 1.9%, 0.9% and 0.9%, respectively. The hospitalisation duration was 14 [11–16] days. The gradients of peak and mean pressure on the aortic valve after surgery were 9 [7–13] and 4 [3–6] mmHg, respectively, and the effective valve opening area was 2.6 [2.3–2.9] cm². None of the patients had moderate and severe aortic regurgitation. The 3-year overall survival and freedom from reoperation were 88.6% and 97%, respectively.</p><p><strong>Conclusion.</strong> The Ozaki operation in patients aged ≥65 years has good immediate results, with a hospital mortality rate of 1.9%, excellent haemodynamic parameters with an average pressure gradient across the aortic valve of 4 [3–6] mmHg and a valve opening area of 2.6 [2.3–2.9] cm². The 3-year overall survival and freedom from reoperation were 88.6% and 97%, respectively. Further monitoring of these patients is required to evaluate long-term results, and there is also a need for randomised clinical trials comparing Ozaki operation with bioprostheses.</p><p>Received 4 February 2021. Revised 21 June 2021. Accepted 23 June 2021.</p><p><strong>Funding:</strong> The study did not have sponsorship.</p><p><strong>Conflict of interest:</strong> Authors declare no conflict of interest.</p><p><strong>Contribution of the authors<br /> </strong>Conception and study design: I.I. Chernov, R.N. Komarov, D.G. Tarasov, Yu.S. Sinelnikov, A.V. Marchenko, V.B. Arutyunayan, K.Yu. Zhigalov<br /> Data collection and analysis: B.K. Kadyraliev, A.M. Ismailbaev, B.M. Tlisov, D.A. Zorin, M.I. Tcheglov<br /> Statistical analysis: S.T. Enginoev<br /> Drafting the article: I.I. Chernov, S.T. Enginoev<br /> Critical revision of the article: I.I. Chernov, R.N. Komarov, D.G. Tarasov, Yu.S. Sinelnikov, A.V. Marchenko, V.B. Arutyunayan, K.Yu. Zhigalov<br /> Final approval of the version to be published: I.I. Chernov, S.T. Enginoev, R.N. Komarov, D.G. Tarasov, Y.S. Sinelnikov, A.V. Marchenko, V.B. Arutyunayan, B.K. Kadyraliev, A.M. Ismailbaev, B.M. Tlisov, D.A. Zorin, M.I. Tcheglov, K.Yu. Zhigalov</p>

Big Data Analytics Maximizes Value from Smart Well Completions

This paper presents a workflow based on big data analytics to model the reliability of downhole Inflow Control Valves (ICVs) and predict their failures. The paper also offers economic analysis of optimum ICV stroking frequency to maintain valves functionality at the lowest possible cost to the oilfield operator. Installing an ICV in a petroleum well is a costly process and is done by a drilling or workover rig. As such, maintaining a fully functional ICV throughout the lifecycle of a well is important to ensure proper return on investment. ICVs are known to malfunction if not periodically stroked/cycled. The action of stroking ensures that each valve opening is free from obstructing material that would prevent the ICV from operating between one valve opening step to another. When an ICV malfunctions, a costly functionality restoration operation is sometime required without guaranteed results. In other cases, the valve is declared no longer useful and the asset cannot be further utilized due to malfunction. In this paper, an analytical decision making model to predict failures of ICVs is presented that is based on rigorous big data analytics. The model factors in the frequency of stroking before a valve fails. Then, an economic analysis accounting for the CAPEX & OPEX of an ICV is included to optimize the stroking frequency. The utilized techniques include ICV failure and stroking records and classifying the data into pre-defined criteria. Cumulative probability distribution functions are defined for each data set and used to generate failure probability functions. The probability equations are factored into an asset management cost scheme to minimize expected maintenance costs and probability of ICV failure. The results of applying this novel methodology to any smart well clearly showed maximized ICV service life and proper return of investment. The results demonstrate that ICVs lifecycle was prolonged with low maintenance cycling cost. Methodologies similar to the one presented in this paper are true manifestation of the fruitful impact IR4.0 technologies have on oilfields day-to-day operations.

Production of Fertilizer from Seawater with a Remote Control System

Seawater is abundant and full of nutrients known as ORMUS. Inorganic fertilizers have become scarce and expensive, so alternatives to feed plants are being studied. An automatic tank on a fishing boat was designed to extract salts from seawater, as follows: Sodium hydroxide is applied to seawater and agitated within a tank until its pH reaches 10.78. Salts begin to deposit, and the sodium mixed with the water stays at the surface. Water with sodium is removed after 3 h with a low-pressure pump. Clean water is added to the salty solution at the bottom of the tank to remove more sodium. Water at the top is sucked by the pump again, and the process is repeated once more. After the white salt (ORMUS) lying at the bottom of the tank is removed, the fertilization extraction process can start again. The automatic system regulates the agitator speed, pump filling and suction timing, and bottom valve opening.

Effects of passive pre-chamber jet ignition on combustion and emission at gasoline engine

Pre-chamber jet ignition is a promising way to improve fuel consumption of gasoline engine. A small volume passive pre-chamber was tested at a 1.5L turbocharged GDI engine. Combustion and emission characteristics of passive pre-chamber at low-speed WOT and part load were studied. Besides, the combustion stability of the passive pre-chamber at idle operation has also been studied. The results show that at 1500 r/min WOT, compared with the traditional spark ignition, the combustion phase of pre-chamber is advanced by 7.1°CA, the effective fuel consumption is reduced by 24 g/kW h, and the maximum pressure rise rate is increased by 0.09 MPa/°CA. The knock tendency can be relieved by pre-chamber ignition. At part load of 2000 r/min, pre-chamber ignition can enhance the combustion process and improve the combustion stability. The fuel consumption of pre-chamber ignition increases slightly at low load, but decreases significantly at high load. Compared with the traditional spark ignition, the NOx emissions of pre-chamber increase significantly, with a maximum increase of about 15%; the HC emissions decrease, and the highest decrease is about 36%. But there is no significant difference in CO emissions between pre-chamber ignition and spark plug ignition. The intake valve opening timing has a significant influence on the pre-chamber combustion stability at idle operation. With the delay of the pre-chamber intake valve opening timing, the CoV is reduced and can be kept within the CoV limit.

Simulation Research on System Characteristics of Valve Opening Curve of Bidirectional Water Transfer System

Due to long pipelines, complex hydraulic conditions, and high flow rate, Bidirectional Water Transfer System of ship is prone to producing Water Hammer Effect when the valve opens and closes, which has a great impact on the pipeline system. In this paper, Flowmaster software is used to simulate the Bidirectional Water Transfer System to study the system characteristics under different valve opening curves. The simulation results show that when the valve opens and closes, Bidirectional Water Transfer System will have a large pressure mutation. But the pressure changes of the stepped and the stepped curve opening curves are smaller and smoother than that of the linear opening curve. But the stepped and the stepped curve opening curves can’t eliminate the pressure and flow rate mutation when the valve opens and closes; In addition, the stepped and the stepped curve opening curves can effectively improve the phenomenon of water flowing out of the reservior, and effectively avoid the phenomenon of gas flowing into the reservior.

Comparative analysis of transient valve-induced flow characteristics between opening and closing processes

Transient control of process valves, including opening and closing processes, is consistently encountered in many fluid transportation and control industries. During opening and closing processes, valve-induced transient flow presents different unstable flow characteristics. This transient valve-induced unstable flow that develops along the pipeline can cause violent pressure and velocity fluctuations that considerably influence accurate flow measurement downstream. In this paper, gate valve-induced flow characteristics during opening and closing processes were comparatively studied. An experimental system was developed to monitor the downstream pressure along the pipeline, and corresponding transient numerical simulations were performed on opening and closing processes using a user-defined function and dynamic grid technology. The pressure distributions along the pipeline's downstream area during valve opening and closing processes were investigated to verify the accuracy of the numerical simulation. The mechanism of transient flow difference under the same valve opening during opening and closing processes was determined to be a hysteresis effect. The jet flow intensity under a small valve opening in the opening process was greater than that in the closing process, and the difference in flow field under the 50% valve opening was the largest. Moreover, the velocity and turbulent kinetic energy distributions in different downstream cross-sections during valve opening and closing processes were comparatively analyzed. The change rate of the maximum turbulent kinetic energy was introduced to further analyze the different effects of opening and closing processes on the transient flow stability downstream of the valve. Results showed that the flow stability between 40% and 50% valve opening was the worst irrespective of the adjustment process, that is, a large pipeline distance was required to stabilize this transient flow. This study helps in understanding transient valve-induced flow characteristics in fluid transportation pipelines and provides guidance for accurate flow metering industrial applications.

Application of Smart Materials in the Actuation System of a Gas Injector

This paper presents the results of research related to the selection of materials for passive and active components of a three-layer piezoelectric cantilever converter. The transducer is intended for use in a low-pressure gas-phase injector executive system. To ensure the functionality of the injector, its flow characteristics and the effective range of valve opening had to be determined. Therefore, a spatial model of the complete injector was developed, and the necessary flow analyses were performed using computational fluid dynamics (CFD) in Ansys Fluent environment. The opening and closing of the injector valve are controlled by a piezoelectric transducer. Thus, its static electromechanical characteristics were found in analytical form. On this basis, the energy demand of the converter, required to obtain the desired valve opening, was determined. Assuming a constant transducer geometry, 40 variants of material combinations were considered. In the performed analyses, it was assumed that the passive elements of the actuator are made of typical materials used in micro-electromechanical systems (MEMSs) (copper, nickel, silicon alloys and aluminum alloys). As for the active components of the converter, it was assumed that they could be made of polymeric or ceramic piezoelectric materials. On the basis of the performed tests, it was found that the energy demand is most influenced by the relative stiffness of the transducer materials (Young’s modulus ratio) and the piezoelectric constant of the active component (d31). Moreover, it was found that among the tested material combinations, the transducer made of silicon oxide and PTZ5H (soft piezoelectric ceramics) had the lowest energy consumption.

A Method to Resolve Simulation of Discontinuous Flow Field: a Valve Example From Full Closing to Re-Closure

In transient computational fluid dynamics (CFD) simulations, the continuity of the flow field is an essential prerequisite. However, continuous flows can be separated under certain conditions, such as the process from valve opening to re-closure. The current method often leaves a narrow gap to estimate the full closing status, which will introduce a deviation. To address this issue, a full closing numerical simulation method (FCNSM) is developed to solve the problem of simulation between discontinuous flow field (DFF) and continuous flow field (CFF). The matrix laboratory (MATLAB) program has been used to communicate Fluent as a server session to call the files Fluent and automatically execute text-based user interface (TUI) commands. The radial basis function (RBF) is used to construct the relationship between the variables of the flow field and the coordinates of mesh nodes, which can achieve the data transmission from a DFF to a CFF. Automatic stopping of transient calculations is achieved by passing variables among MATLAB program, scheme language, and user-defined functions (UDF) when a physical quantity reaches a set value. Based on this method, a transient simulation with a dynamic mesh of a 2-D model regarding a pressure relief valve (PRV) is performed to simulate the process of the valve from full closing to re-closure, the flow characteristics through the PRV are obtained using this method. This study makes it possible to use FCNSM for understanding dynamic characteristics from DFF to CFF.