scholarly journals Methods of calculation of energy losses of the refrigerator when opening its doors

2018 ◽  
Vol 215 ◽  
pp. 01018
Author(s):  
S.P. Petrosov ◽  
M.A. Lemeshko ◽  
A.V. Kozhemyachenko ◽  
S.E. Bashnjak
Keyword(s):  
Mass Transfer ◽  
Energy Efficiency ◽  
Energy Consumption ◽  
Global Economy ◽  
Air Flow ◽  
Experimental Studies ◽  
Ambient Air ◽  
Modern World ◽  
Functional Dependencies ◽  
Navier Stokes Equation

The problem of energy supply and the problem of energy efficiency of energy consumers are global problems. In the modern world, scientists pay much attention to the tasks of creating new and improving traditional sources of electricity. The tasks of increasing the energy efficiency of electricity consumers remain relevant in the global economy. One of the relatively capacious energy consumers is the Park of refrigerators, household and commercial purposes, which are also being improved in order to increase their energy efficiency. Modernization and improvement of household and commercial refrigerators include the task of designing and using more efficient refrigerators. Energy consumption of compression refrigerators, along with other operational factors, depends on the processes of heat exchange and mass transfer of air from internal chambers to the ambient air. When the doors of the refrigerator chambers are opened, the cooled air in the chambers is replaced with the warmer air of the environment. This process causes the cost of operation of the refrigeration machine and characterizes its energy consumption. In order to minimize this power consumption, knowledge of the process of cool air outflow of their open refrigerator chambers is required. Currently, this process is poorly understood. The article presents an approach to the description of the process of motion of the cooled air from the refrigerator chamber, the main assumptions necessary for the construction of a mathematical model of this process are given, and a method for calculating the heat in the refrigerator chambers associated with the replacement of the cooled air with the ambient air inside the chambers is proposed. The method is based on the laws of gas dynamics, supplemented by some experimental studies. In particular, the well — known Navier-Stokes equation is used as the initial basis. This equation supplemented by the continuity equation of the air flow and other functional dependencies. As a result of mathematical transformations and arguments about the physics of the mass transfer process, finite equations are obtained, which allow describing both the performance of the cooled air flow and the amount of heat introduced into the chambers by external warm air. Mathematical dependences are developed for calculation of parameters of motion of a stream of the cooled air and heat inflows, thus the temperature of ambient air and temperature in chambers of the refrigerator are considered. The results of the research will be useful in the design of new refrigerating machines with reduced energy consumption.

scholarly journals Increase of the energy efficiency in paper industry

2008 ◽  
Vol 62 (4) ◽  
pp. 233-245
Author(s):  
Milorad Krgovic ◽  
Vladimir Valent ◽  
Marina Krsikapa ◽  
Miodrag Milojevic ◽  
Branko Raseta ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Energy Efficiency ◽  
Energy Consumption ◽  
Specific Heat ◽  
Paper Industry ◽  
Electric Energy ◽  
Paper Drying ◽  
Improve Energy Efficiency ◽  
Electric Energy Consumption ◽  
Paper Machines

In this work, phenomena of heat and mass transfer in process of paper drying are given, certain technology units are analyzed, while possibility for decrease of specific heat and electric energy consumption by modernization of technology is examined. Some of the solutions applied on paper machines worldwide in order to improve energy efficiency are shown. Theoretic and practical discoveries in this area are applied in Board factory UMKA, and these results are shown in the work as well.

Dimethyl Ether as a Novel Solvent for Bitumen Recovery: Mechanisms of Improved Mass Transfer and Energy Efficiency

SPE Journal ◽  
2021 ◽  
pp. 1-20
Author(s):  
Min Yang ◽  
Maojie Chai ◽  
Rundong Qi ◽  
Zhangxin Chen ◽  
Linyang Zhang ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Energy Efficiency ◽  
Energy Consumption ◽  
Dimethyl Ether ◽  
Oil Production ◽  
Recovery Process ◽  
Thermal Recovery ◽  
Production Performance ◽  
Reservoir Rock ◽  
Bitumen Recovery

Summary A solvent-based thermal recovery process has the advantages of low capital expenditure, less energy consumption, and less greenhouse gas emission. Dimethyl ether (DME), as a renewable solvent, has been considered as a novel additive in the thermal bitumen recovery process. Being soluble in both water and oil phases, DME has the potential to enhance mass transfer and improve oil production. In this work, a phase behavior model of the DME-bitumen-water system is first developed considering DME partitioning between oil and water. A field-scale numerical simulation model with fine gridblocks is developed to investigate the heat and mass transfer mechanisms between DME and bitumen in the interface of a DME vapor chamber. The numerical model is validated with physical experiment results. The close agreement between measured and simulated production profiles indicates that the mechanisms are adequately captured. Meanwhile, various simulation scenarios are performed to evaluate the production performance and the energy efficiency, which is defined as the energy/oil ratio. It is found that the oil production rate in DME injection is 15% higher than that in butane injection at the early stage of production. The solvent penetration depth in DME injection is larger than that in butane injection. This is attributed to the enhanced mass transfer between DME and bitumen caused by the high diffusion of DME in the water phase and preferential partitioning of DME into the oil phase. Furthermore, energy consumption in the warm DME injection process is 48% less than that in warm butane injection and 75% less than that in steam-assisted gravity drainage (SAGD). This is because DME injection can be operated at a lower-temperature condition, leading to less energy transferred to heat reservoir rock/fluids and less heat loss to over/underburden. Therefore, DME is proved to be a technically promising and environmentally friendly solvent to enhance bitumen recovery. The DME-based thermal recovery technique exhibits superior advantages in unlocking poor-quality reservoirs, especially in high water saturation reservoirs and thin reservoirs.

scholarly journals Phase Change Materials for Energy Efficiency in Buildings and Their Use in Mortars

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1260 ◽  
Author(s):  
Mariaenrica Frigione ◽  
Mariateresa Lettieri ◽  
Antonella Sarcinella
Keyword(s):  
Energy Efficiency ◽  
Energy Consumption ◽  
Phase Change ◽  
Construction Industry ◽  
Phase Change Materials ◽  
Experimental Studies ◽  
New Materials ◽  
Human Comfort ◽  
Temperature Variations ◽  
Building Systems

The construction industry is responsible for consuming large amounts of energy. The development of new materials with the purpose of increasing the thermal efficiency of buildings is, therefore, becoming, imperative. Thus, during the last decades, integration of Phase Change Materials (PCMs) into buildings has gained interest. Such materials can reduce the temperature variations, leading to an improvement in human comfort and decreasing at the same time the energy consumption of buildings, due to their capability to absorb and release energy from/in the environment. In the present paper, recent experimental studies dealing with mortars or concrete-containing PCMs, used as passive building systems, have been examined. This review is mainly aimed at providing information on the currently investigated materials and the employed methodologies for their manufacture, as well as at summarizing the results achieved so far on this subject.

Low Temperature Drying With Air Dehumidified by Zeolite for Food Products: Energy Efficiency Aspect Analysis

2011 ◽  
Vol 7 (6) ◽  
Author(s):  
Mohamad Djaeni ◽  
C. J. van Asselt ◽  
P. V. Bartels ◽  
J. P. M. Sanders ◽  
Gerrit van Straten ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Low Temperature ◽  
Air Flow ◽  
Food Products ◽  
Ambient Air ◽  
Minor Effect ◽  
Total Work ◽  
Interesting Issue ◽  
A Minor ◽  
Low Temperature Drying

Developments in low temperature drying of food products are still an interesting issue; especially with respect to the energy efficiency. This research studies the energy efficiency that can be achieved by a dryer using air which is dehumidified by zeolite. Experimental results are fitted to a dynamic model to find important variables for the drying operation. The results show that ambient air temperature as well as the ratio between air flow for drying and air flow for regeneration, affect the energy efficiency significantly. Relative humidity of used air, and shift time have a minor effect on the dryer performance. From the total work, it can be noted that the dryer efficiency operated at 50-60°C achieves 75 percent, which is attractive for drying of food products.

scholarly journals GLOBAL TRENDS IN THE DEVELOPMENT OF ENERGY-SAVING TECHNOLOGIES

2020 ◽  
pp. 31-43
Author(s):  
S. Gushchin ◽  
A. Seminenko ◽  
Chao Shen
Keyword(s):  
Energy Efficiency ◽  
Energy Consumption ◽  
Energy Saving ◽  
State Level ◽  
Hot Water ◽  
Energy Resources ◽  
Historical Background ◽  
Modern World ◽  
Improve Energy Efficiency ◽  
The World

The need to provide heat, hot water and electricity are the basic needs of society, and throughout the history of mankind, they form the greatest demand for energy resources. In the modern world, energy consumption by countries all over the world is constantly increasing; it’s creating new problems such as lack of energy resources, their rise in price, depletion of energy sources, environmental threats, and others. In connection with the problem of saving, rational and efficient use of energy resources and huge energy losses in the construction industry, this article considers world experience of application of energy-saving technologies and other measures to improve energy efficiency, analyzes the current situation in the field of energy saving in Russia. Prerequisites to the study of energy efficiency problems are considered, state of energy consumption and energy saving in China, USA, some EU countries and Russia is analyzed, the world experience of application ways of energy efficiency improving at the state level is considered. The problems and historical background that hinder the development of Russia in the field of energy saving are discussed. Specific proposals to improve energy efficiency in Russia have been put forward based on an analysis of international experience.

scholarly journals Experimental studies of the efficiency of high-speed ESPs

2021 ◽  
Vol 266 ◽  
pp. 01023
Author(s):  
D.B. Zhigarev ◽  
A.V. Lekomtsev ◽  
A.E. Gorlov ◽  
A.V. Dengaev
Keyword(s):  
Energy Efficiency ◽  
High Speed ◽  
Rotation Speed ◽  
Experimental Studies ◽  
Field Tests ◽  
Bench Test ◽  
Functional Dependencies ◽  
Suggested Approach ◽  
Operational Conditions ◽  
Adjustment Factors

The purpose of the present research paper is to estimate the energy efficiency of ESP-operated low production rate wells (up to 100 m3/d).The data on pumps energy efficiency, including the high-speed ESPs, were consolidated and analyzed. The bench test of high-speed ESPs and comparison with field tests allowed to determine the efficiency adjustment factors and establish functional dependencies of energy parameters on shaft rotation speed;theobtainedcorrelations were suggested for recalculation of nominalvalues in bench tests. The paper also indicates that the average efficiency for the high speed ESPs is 12-17% higher in absolute values and 40-68% higher in relative values, compared with the efficiency of pumps with a nominal rotation speed of 3000 rpm. The suggested approach can be expanded as a methodology for wells with more complex operational conditions and more complex pump systems.

Globalization and interconfessional communications

2001 ◽  
pp. 13-17
Author(s):  
Serhii Viktorovych Svystunov
Keyword(s):  
21St Century ◽  
Global Economy ◽  
Modern World ◽  
The World ◽  
Target Set ◽  
Almost All ◽  
Over Time ◽  
Rapid Appearance

In the 21st century, the world became a sign of globalization: global conflicts, global disasters, global economy, global Internet, etc. The Polish researcher Casimir Zhigulsky defines globalization as a kind of process, that is, the target set of characteristic changes that develop over time and occur in the modern world. These changes in general are reduced to mutual rapprochement, reduction of distances, the rapid appearance of a large number of different connections, contacts, exchanges, and to increase the dependence of society in almost all spheres of his life from what is happening in other, often very remote regions of the world.

Peculiarities of Modern Dynamics of the Global Economy

2010 ◽  
pp. 78-92 ◽  
Author(s):  
V. Klinov
Keyword(s):  
Economic Growth ◽  
Economic Development ◽  
Business Cycles ◽  
Global Economy ◽  
Long Waves ◽  
Rapid Expansion ◽  
Business Taxation ◽  
Modern World ◽  
China And India ◽  
World Economic

Rates and factors of modern world economic growth and the consequences of rapid expansion of the economies of China and India are analyzed in the article. Modification of business cycles and long waves of economic development are evaluated. The need of reforming business taxation is demonstrated.

Rising Inequality in the New Global Economy

2006 ◽  
pp. 84-89 ◽  
Author(s):  
N. Birdsall
Keyword(s):  
Developing Countries ◽  
Global Economy ◽  
Slow Growth ◽  
Global Markets ◽  
Modern World ◽  
Government Programs ◽  
Poor Countries

Reasons of high inequality in the modern world are considered in the article. In developing countries it interacts with underdeveloped markets and inefficient government programs to slow growth, which in turn slows progress in reducing poverty. Increasing reach of global markets makes rising inequality more likely and deepens the gap between rich and poor countries. Because global markets work better for the already rich, we should increase the representation of poor countries in global fora.

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