Investigation, Analysis and Solution of Higher Noise of Heat Pump Water Heater

The paper made an investigation on noise problems of A.O Smith heat pump water heaters. One problem is that the noise and vibration performance of 1P compressor of wall hanging type water heater was unqualified. The sound pressure level of compressor sample was about 40dBA, and the clients hope to be controlled below 39dBA. Another problem is that the noise of HV-80 floor type water heater is large when used matching with the 1.5P compressor of our company. According to the test and analysis with Test.Lab software, it is found that the main noise came from fan and compressor. The solutions of noise reduction on fan and compressor were made and the consequences were recognized by clients and markets

Research on Noise Reduction of Variable Speed Rotary Compressor with Large Capacity

With the increasing speed and capacity of variable-speed rotary compressors, the problem of noise especially low and medium frequency noise in the air conditioning system which can\u27t be solved by wrapping soundproof cotton has became more serious. In this paper, based on the noise problem of the rotor compressor with a working capacity of more than 80CC, the main frequency and the position of the noise source within 1000Hz are confirmed by simulation and experiment. Then on the base of this，the muffler and accumulator are respectively optimized and improved combining with Computer Aided Engineering (CAE) means. The final application results show that the optimized scheme can reduce noise by 6.1dB in 160Hz and 8.9dB in the frequency range of 500Hz to 800Hz, achieving good results

WeTS - Web Technology Selection Guidelines

Web development is receiving increasing attention among all kinds and sizes of companies. Web presentation has become a hygiene factor for companies nowadays. Fortunately, nowadays web developers can choose from a great number of ready-made technologies instead of developing everything from scratch. However, web development technologies have evolved much in the past 20 years. Due to the increased complexity and diversity of the alternatives, it is getting more and more difficult for companies to make an overall good choice of technologies, especially small and medium-sized enterprises (SMEs) that usually do not have resources to make a thorough research before choosing. This thesis creates WeTS - Web Technology Stack Guidelines, which contains three parts: process, algorithm and software quality characteristics. By following WeTS, inexperienced web developers, especially in SMEs, can select web technology stacks in an optimal way. Meanwhile, WeTS could be used for experienced practitioners and researchers as a reference to have an overview about modern web development technologies. Based on WeTS Guidelines, this thesis evaluated a number of technology stacks. Then a case study was performed with a startup company named Sqore. By comparing WeTS with Sqore’s technology selection process step by step, this thesis evaluated WeTS Guidelines

WeTS - Web Technology Selection Guidelines

Web development is receiving increasing attention among all kinds and sizes of companies. Web presentation has become a hygiene factor for companies nowadays. Fortunately, nowadays web developers can choose from a great number of ready-made technologies instead of developing everything from scratch. However, web development technologies have evolved much in the past 20 years. Due to the increased complexity and diversity of the alternatives, it is getting more and more difficult for companies to make an overall good choice of technologies, especially small and medium-sized enterprises (SMEs) that usually do not have resources to make a thorough research before choosing. This thesis creates WeTS - Web Technology Stack Guidelines, which contains three parts: process, algorithm and software quality characteristics. By following WeTS, inexperienced web developers, especially in SMEs, can select web technology stacks in an optimal way. Meanwhile, WeTS could be used for experienced practitioners and researchers as a reference to have an overview about modern web development technologies. Based on WeTS Guidelines, this thesis evaluated a number of technology stacks. Then a case study was performed with a startup company named Sqore. By comparing WeTS with Sqore’s technology selection process step by step, this thesis evaluated WeTS Guidelines

Enrichment of Smectite in the REY‐Rich Mud of the Clarion‐Clipperton Fracture Zone in the Eastern Pacific and Its Geological Significance

Abstract REY‐rich mud, consisting of deep‐sea sediments with high concentrations of rare‐earth elements and yttrium (REY), holds significant economic potential. Many studies have been conducted on biogenic apatite, ferromanganese micronodule, and phillipsite within these deposits to ascertain the REY enrichment mechanisms. However, the knowledge of clay minerals in REY‐rich mud, which is the predominant component of pelagic sediments, is still limited. In this study, two adjacent gravity cores (core GC02: REY‐rich mud; core GC03: typical sediments of equatorial Pacific) were collected from the Clarion‐Clipperton Fracture Zone (CCFZ) of the Eastern Pacific to study the role of different clay minerals in REY enrichment. The clay minerals in core GC03 and core GC02 are primarily illite (averaging 60%) and smectite (averaging 63%), respectively, and the smectite in core GC02 was mainly Fe‐rich, which was probably formed via the reaction between opal and FeOOH. Moreover, multiple studies have reported similar smectite enrichment in REY‐rich mud, suggesting that it is a common characteristic. The presumed hydrothermal or volcanic origination of smectite in REY‐rich layers of core GC02 indicates the essential role of hydrothermal and volcanic activities in REY‐rich mud formation during the Oligocene in the western CCFZ

Gas Sources, Migration, and Accumulation Systems: The Shallow Subsurface and Near-Seafloor Gas Hydrate Deposits

Compared with the deeply buried marine gas hydrate deposits, gas hydrates in the shallow subsurface, close to and at the seafloor, have attracted more attention owing to their concentrated distribution, high saturation, and easy access. They accumulate at relatively shallow depths <100–120 m and occur as gas hydrate-bearing mounds (also known as hydrate outcrops, pingoes) at the seafloor derived from the growth of hydrates in the shallow subsurface or as pure hydrate chunks formed by gas leakage. This paper reviews and summarizes such gas hydrate systems globally from the perspective of gas sources, migration pathways, and accumulation processes. Here, we divided them into four categories: fault-chimney-controlled, diapir-fault-controlled, fault-controlled, and submarine mud volcano-controlled deposits. Gas chimneys originate immediately above the restricted regions, mostly affected by faults where high gas concentrations trigger elevated pore fluid pressures. Diapirism derives a dendritic network of growth faults facilitating focused gas discharge and hydrate formation near the seafloor. Furthermore, pre-existing faults or fractures created by overpressured gas from greater depths in accretionary tectonics at convergent margins act as preferential pathways channeling free gas upwards to the seafloor. Gas flux rates decrease from the submarine mud volcano center to its margins, creating a concentric pattern of distributing temperature, gas concentrations, and hydrate contents in shallow sediments around the mud volcano. Hydrate-bound hydrocarbons are commonly of thermogenic origin and correspond to high-background geothermal conditions, whereas microbial gas is dominant in a few cases. The presence of heavier hydrocarbons mitigates the inhibition of hydrate formation by salt or heat. Fluid migration and pathways could be compared to the “blood” and “bones” in an organic system, respectively. The root of a pathway serves as the “heart” that gathers and provides considerable free gas concentrations in a restricted area, thereby triggering pore fluid pressures as one important drive force for focused fluid flow in impermeable sediments (the organic system). Besides the suitable temperature and pressure conditions, a prerequisite for the formation and stability of hydrate deposits in the shallow subsurface and at the seafloor is the sufficient supply of gas-rich fluids through the hydrate stability zone. Thus, the proportion of gas migrating from deep sources is significantly larger than that trapped in hydrates. As such, such marine hydrate deposits seem more like temporary carbon storage rather than the main culprit for climate warming at least in a short period

A synergistic Pt-Ru-nitrogen-doped-carbon hydrogen oxidation catalyst

Hydroxide exchange membrane fuel cell (HEMFC) is a potentially cost-effective energy conversion technology. However, current state of the art HEMFCs require a high loading of platinum-group-metal (PGM) catalysts, especially for the hydrogen oxidation reaction (HOR). Here we develop a porous nitrogen-doped carbon-supported PtRu HOR catalyst (PtRu/pN-C) that has the highest reported intrinsic and mass activity in alkaline condition. Spectroscopic and microscopic data indicate the presence of Pt single atoms (SAs) in addition to PtRu nanoparticles on pN-C. Mechanistic study suggests Ru modulates the electronic structure of Pt for an optimized hydrogen binding energy, while Pt-SAs on pN-C optimize the interfacial water structure. These synergetic interactions are responsible for the high catalytic activity of this catalyst. An HEMFC with a low loading of this catalyst and a commercial Fe-N-C oxygen reduction reaction (ORR) catalyst achieves the highest reported PGM utilization rate. The current density at 0.65 V of this HEMFC reaches 1.5 A/cm2, exceeding the US DOE 2022 target (1 A/cm2) by 50 %

Diverse early diagenetic processes of ferromanganese nodules from the eastern Pacific Ocean: evidence from mineralogy and in-situ geochemistry

Ferromanganese nodules are a potential energy resource because of their high contents of economically interesting elements (i.e. Mn, Ni, Cu, and Zn). These are higher in diagenetic layers than in hydrogenetic layers. The study of the causes of elemental accumulation in the diagenetic layer is useful for the exploration metal-rich nodules. A diagenetic-dominant ferromanganese nodule, from the central Clarion–Clipperton Fracture Zone of the eastern Pacific Ocean was studied from core to rim. It was divided into four layers and seven sublayers, of the four typical diagenetic sublayers (L1, L2-1, L2-2, and L3-1). Differences were observed in these diagenetic sublayers. L1 presents the highest Mn/Fe ratio (54), the lowest Co content (2262 ppm), and a positive Ce anomaly. L2-1 exhibits high Co (3122 ppm) and Ba contents (4020 ppm), a positive Ce anomaly, and an obvious peak for 10 Å manganate minerals. L2-2 contains the lowest Ni+Cu contents (3.2 wt%), the highest Ba and Co contents (5110 ppm), and the strongest positive Ce anomaly. In L2-2, the δCe value can be positively correlated to the Mn/Fe ratio and a pronounced peak for 10 Å manganate minerals indicates that this layer has the highest mineral crystallinity. L3-1 shows the highest Ni+Cu contents (5.4 wt%), the lowest Ba (1247ppm), and Co (1725 ppm), a weakly positive Ce anomaly, and the poorest mineral crystallization. Diagenetic- and hydrogenetic-endmember mixing models reveal that hydrogenetic input contributes minimally to these chemical changes, whereas diagenetic input contributes greatly. The changes in diagenetic input may be caused by the changes in primary productivity brought about by movement of tectonic plates and the intense activity of the diagenetic pore fluid. The activity may provide a metal source for the diagenetic sublayer (anomalously high Co and Ce content) via the incorporation of metals released from dissolved buried nodules and micronodules under a suboxic or reducing environments.</p