The Effect of Water Impact on the Refrigerant Pipeline between Compressor and Condensor on COP and Efficiency of Cooling Machine

The purpose of this research is (a) to design and assemble a steam compression cycle cooling machine using the main components on the market (b) to obtain the characteristics of the cooling engine, which includes the Coefficient of Performance (COP) and the efficiency of the cooling engine. The research was conducted experimentally in the laboratory. The refrigeration machine works by using a steam compression cycle, with the main components: a compressor, an evaporator, a capillary tube and a condenser. The compressor power is 1/6 PK, while the other main components are adjusted to the size of the compressor power. The refrigerant used is R134a. Variations of the research were carried out on the condition of the refrigerant pipe located between the compressor and condenser: (a) without being submerged in water (b) submerged in 0.50 liters of water and (c) submerged in 0.75 liters of water. The results of the study provide information that the water immersion in the refrigerant pipe which is located between the compressor and condenser affects the COP value and the efficiency of the refrigeration machine. Consecutively (1) without being submerged in water, the COP value is 2.45 and the efficiency is 0.64 (2) submerged in liter of water, the COP value is 2.41 and the efficiency is 0.62 (3) submerged in liter of water, the value COP is 2.34 and efficiency is 0.60.

ASYMMETRICAL WATER IMPACT OF TWO-DIMENSIONAL WEDGES WITH ROLL ANGLE WITH MULTI-MATERIAL EULERIAN FORMULATION

A hydrodynamic study on the asymmetrical water impact of two-dimensional wedges with roll angle is presented. The slam induced loads on the wedges entering calm water with both vertical and horizontal velocities are predicted based on the explicit finite element method. The effects of the horizontal impact velocity and the roll angle are investigated through the predicted results of pressure distribution, pressure variation during the water entry and total impact force, which are also compared with analytical formulations and other numerical calculations. The present method gives reasonable predictions, compared to the numerical and analytical results.

Durability of UHPFRC functionalised with nanoadditives due to synergies in the action of sulphate and chloride in cracked and uncracked states

This paper studies the durability of Ultra High Performance Fibre Reinforced Concrete (UHPFRC) with high Blast Furnace Slag content (BFS) and nanoadditives such as crystalline admixture (CA), alumina nanofibres (ANF) and cellulose nanocrystals (CNC), exposed to different aggressive environmental conditions: 1) three aggressive media: a) deionized water (dw), b) sulphate rich solution (ss) and c) simulated geothermal water (sgw) containing sulphate and chloride; 2) two water interaction conditions: a) static and b) dynamic (water impact); and 3) with and without the presence of cracks. Durability was analysed over 24 months, measuring several physical and chemical parameters of the system, recording changes in both the aggressive media and the concrete. All UHPFRC types demonstrate good durability, showing high resistance to expansion and deformation in the sulphate-rich media. A leaching process occurs in all water interaction systems, the dynamic interaction in sgw being the most aggressive. The interaction of sgw inside the crack favours the formation of solid phases such as calcium carbonates and ettringite, while the presence of nanoadditives affects the response of both the matrix and the formation of precipitates within the crack.

Interaction of Nanodiamonds with Water: Impact of Surface Chemistry on Hydrophilicity, Aggregation and Electrical Properties

In recent decades, nanodiamonds (NDs) have earned increasing interest in a wide variety of research fields, thanks to their excellent mechanical, chemical, and optical properties, together with the possibility of easily tuning their surface chemistry for the desired purpose. According to the application context, it is essential to acquire an extensive understanding of their interaction with water in terms of hydrophilicity, environmental adsorption, stability in solution, and impact on electrical properties. In this paper, we report on a systematic study of the effects of reducing and oxidizing thermal processes on ND surface water adsorption. Both detonation and milled NDs were analyzed by combining different techniques. Temperature-dependent infrared spectroscopy was employed to study ND surface chemistry and water adsorption, while dynamic light scattering allowed the evaluation of their behavior in solution. The influence of water adsorption on their electrical properties was also investigated and correlated with structural and optical information obtained via Raman/photoluminescence spectroscopy. In general, higher oxygen-containing surfaces exhibited higher hydrophilicity, better stability in solution, and higher electrical conduction, although for the latter the surface graphitic contribution was also crucial. Our results provide in-depth information on the hydrophilicity of NDs in relation to their surface chemical and physical properties, by also evaluating the impacts on their aggregation and electrical conductance.

Microplastic Pollution in Waters and its Impact on Health and Environment in Indonesia: A Review

Introduction: Microplastics have become a pollution problem that has received worldwide attention. Microplastics in the water impact the environment and health, especially in Indonesia, which is the second-largest plastic waste contributor in the world. This literature study aims to determine the distribution of microplastics pollution in waters and its impact on health and the environment in Indonesia.Methods: The literature search on papers from 2010-2021 through Google Scholar, Pubmed, ScienceDirect, and ProQuest, with the keywords of ‘Microplastics’, ‘Indonesia’, ‘aquatic’, ‘environment’ found 477 articles. Then, after the exclusion of duplicate articles, and other inclusion criteria, the final review was done on 42 articles. PRISMA guidelines were used for reviewing the procedure.Results: Most microplastic research was conducted in Java Island, which is dominated by rivers and beaches. Based on the source, microplastics came from domestic waste, tourism, and fishing activities. The most common forms found were black and blue fibers from fishing lines, nets, and clothing fibers of various sizes. The type of polymer identified is polyethylene plastic. Microplastics impacted tourist destinations, marine ecosystems through the food chain, and also humans who consume seafood.Conclusion: Microplastics are found in the Indonesian marine environment. Humans can consume seafood contaminated with microplastics, which will have an impact on health. Therefore, a health risk assessment should be done to provide information for taking environmental management efforts.

Analytical review of underground equipment of water impact operation for well development

Rational indicators for the development of oil and gas fields are related to the systemic maintenance of a given level of perfection of formation opening in bottomhole zones of producing or injection wells. This need arises with the colmatation of the natural collector by mechanical, asphalt and tar-paraffinic particles, leading to a decrease in productivity, acceptance of wells and the need to restore the inflow by methods of artificial action on the bottomhole formation zone. Analysis of the effectiveness of the application of various methods of stimulating the flow of reservoir products in the fields of the Timan-Pechora oil and gas province (based on field data) allowed to argue the success of using hydraulic fracturing, thermogas chemical, and shock-depressive effects on the bottomhole formation zone. The prospect of the development of technical means for impact-depressive (implosion) impact on the bottomhole formation zone favorably distinguished by simplicity, cheapness, manufacturability and accessibility is shown. The designs of implosion hydrogenerators of single and multiple pressure are analyzed, shortcomings of technical devices are identified and ways of improving mechanisms are outlined. The results of effective application of various downhole generator devices for increasing productivity and well acceptance are presented.