Behavior and Performance of Refrigerant Mixture HFC125/HC290 in Heat Pumps

2013 ◽  
Author(s):  
Xiaowei Fan ◽  
Fang Wang ◽  
Huifan Zheng ◽  
Xianping Zhang ◽  
Di Xu
Keyword(s):  
Energy Consumption ◽  
Heat Pumps ◽  
Operating Conditions ◽  
Environment Friendly ◽  
Factors Affecting ◽  
Refrigerant Mixture ◽  
Important Direction ◽  
Overall Performance ◽  
And Performance ◽  
Binary Refrigerant

The refrigerant mixtures provide an important direction in selecting new environment-friendly alternative to match the desirable properties with the existing halogenated refrigerants or future use in the new devices, in which, HFCs refrigerants with zero ODP combined with HCs refrigerants with zero ODP and lower GWP are of important value in the fields of application. In the present work, research on HFC125/HC290 (25/75 by mass) binary refrigerant mixture used in heat pumps was carried out, and parameters, factors affecting the performance were investigated, and compared with that of HCFC22 under the same operating conditions. It has been found that the new mixture can improve the actual COP by 2 to 13% and hence it can reduce the energy consumption by 20 to 31.5%. The overall performance has proved that the new refrigerant mixture could be a promising substitute for HCFC22.

scholarly journals Current Advances in Ejector Modeling, Experimentation and Applications for Refrigeration and Heat Pumps. Part 2: Two-Phase Ejectors

Inventions ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 16 ◽  
Author(s):  
Zine Aidoun ◽  
Khaled Ameur ◽  
Mehdi Falsafioon ◽  
Messaoud Badache
Keyword(s):  
Heat Pumps ◽  
Operating Conditions ◽  
Industrial Processes ◽  
Experimental Investigations ◽  
Mixing Enhancement ◽  
Data Generation ◽  
Two Phase ◽  
Wide Range ◽  
Potential Applications ◽  
And Performance

Two-phase ejectors play a major role as refrigerant expansion devices in vapor compression systems and can find potential applications in many other industrial processes. As a result, they have become a focus of attention for the last few decades from the scientific community, not only for the expansion work recovery in a wide range of refrigeration and heat pump cycles but also in industrial processes as entrainment and mixing enhancement agents. This review provides relevant findings and trends, characterizing the design, operation and performance of the two-phase ejector as a component. Effects of geometry, operating conditions and the main developments in terms of theoretical and experimental approaches, rating methods and applications are discussed in detail. Ejector expansion refrigeration cycles (EERC) as well as the related theoretical and experimental research are reported. New and other relevant cycle combinations proposed in the recent literature are organized under theoretical and experimental headings by refrigerant types and/or by chronology whenever appropriate and systematically commented. This review brings out the fact that theoretical ejector and cycle studies outnumber experimental investigations and data generation. More emerging numerical studies of two-phase ejectors are a positive step, which has to be further supported by more validation work.

scholarly journals Improving Employee Performance in Industrial Parks: An Empirical Case of Garment Enterprises in Binh Duong Province, Vietnam

2019 ◽  
Vol 10 (1) ◽  
pp. 44-58
Author(s):  
Thanh-Lam Nguyen ◽  
Pham Xuan Giang
Keyword(s):  
Employee Performance ◽  
Key Factors ◽  
Factors Affecting ◽  
Overtime Work ◽  
Industrial Parks ◽  
Overall Performance ◽  
Job Promotion ◽  
And Performance ◽  
Fierce Competition ◽  
Reward And Recognition

In responding to the current international integration and fierce competition on marketplace, over the last few decades, most businesses have tried to continuously improve their performance for better competitiveness. One of the preferred approaches is to enhance their employee performance; thus, fully capturing its determinants is critical. Thus, this study aimed at identifying key factors affecting employee performance so that businesses can create proper policies and actions to improve their overall performance. Specifically, as a common phenomenon, most employees working in industrial parks not only live far away from their workplaces as well as work a lot of overtime. These issues were carefully considered in this study to investigate their impacts on the employee satisfaction and performance. In the empirical case of garment enterprises in Binh Duong industrial parks, it was found that job satisfaction and employee performance are positively affected by eight factors: (1) reward and recognition; (2) development and training; (3) job promotion; (4) income; (5) work environment; (6) relationship with superiors; (7) relationship with colleagues; and (8) work procedure and role. In addition, it was found to be negatively affected by the house–work distance and overtime work, which are two new factors proposed in this study.

scholarly journals Theoretical and Practical Aspects of Biological Sulfate Reduction: A Review

2019 ◽  
Keyword(s):  
Sulfate Reduction ◽  
Life Forms ◽  
Operating Conditions ◽  
Community Formation ◽  
Operational Cost ◽  
Efficient Treatment ◽  
Physicochemical Processes ◽  
Overall Performance ◽  
And Performance ◽  
Biological Sulfate Reduction

<p>The major environmental impact of discharge of excessive quantities of sulfate is the pollution of the surface and ground water supplies which can be harmful to life forms and therefore the need for an efficient treatment system arises. Biological sulfate reduction offers the advantage of less sludge production, less operational cost and efficiency in comparison to the physicochemical processes. Depending upon the feeding and operating conditions as well as microbes used, a number of intermediates are formed that may greatly affect the overall performance of bioreactor. This article extensively explores the bacterial community, formation of intermediates and desirable end products, theoretical and practical aspects of various environmental and operating conditions, and performance of bioreactors used for treating sulfate rich wastewater along with process biokinetics involved in biological sulfate reduction.</p>

scholarly journals An analysis of the viability of implementing steam screw machines at the facilities of energy generation enterprises to reduce the energy costs for their own need

2019 ◽  
Vol 124 ◽  
pp. 01016 ◽  
Author(s):  
D. S. Balzamov ◽  
I. G. Akhmetova ◽  
E. Y. Balzamova ◽  
G. I. Oykina ◽  
Gelu COMAN
Keyword(s):  
Water Vapor ◽  
Energy Consumption ◽  
Potential Energy ◽  
Energy Generation ◽  
Operating Conditions ◽  
Energy Sources ◽  
Energy Costs ◽  
Factors Affecting ◽  
Urgent Task ◽  
Current Operating

Reducing the energy consumption for the own needs of energy sources is an urgent task that can be solved by organizing our own energy sources by using the potential energy of water vapor in steam screw machines. The article discusses some options for installing steam screw machines at the facilities of generating companies and identifies factors affecting the return on steam screw machines in the current operating conditions.

Performance of a Two-Phase Injection Heat Pump with the Variation of Injection Quality and Pressure

2017 ◽  
Vol 25 (02) ◽  
pp. 1750018 ◽  
Author(s):  
Bo Gyeom Kim ◽  
Dongwoo Kim ◽  
Dongchan Lee ◽  
Yongchan Kim
Keyword(s):  
Heat Pump ◽  
Operating Parameter ◽  
Heat Pumps ◽  
Operating Conditions ◽  
Two Phase ◽  
High Discharge ◽  
Discharge Temperature ◽  
Vapor Injection ◽  
And Performance ◽  
Compressor Reliability

Heat pumps are becoming more commonly and widely used due to their advantages in efficiency and versatile applications in both cooling and heating. However, the reliability of its compressor is being compromised due to high discharge temperatures caused by harsh operating conditions. Among the numerous studies conducted in improving the discharge temperature and performance of the heat pump, two-phase injection is receiving great interest. In this study, the performance of the two-phase injection heat pump was measured with a variation of operating parameters. The experiment results were used to study the performance change according to the operating parameter such as injection quality and pressure. It was found that the performance of the heat pump using the two-phase injection was better in terms of COP by up to 5.8% compared to that using the vapor injection. Furthermore, the two-phase injection was effective in reducing the discharge temperature to improve the compressor reliability. Two types of optimum injection qualities were suggested through this study: discharge temperature optimum injection quality (TIQ), and performance optimum injection quality (PIQ). It was found that in most conditions PIQ was sufficient in satisfying the compressor reliability, but in harsh operating conditions, where the compression ratio was high, TIQ was required in order to maintain the compressor reliability.

An Automatic Car Heater System-Description and Performance Prediction

1968 ◽  
Vol 183 (1) ◽  
pp. 125-135
Author(s):  
A. G. Plackett
Keyword(s):  
Performance Prediction ◽  
Digital Computer ◽  
System Parameter ◽  
Operating Conditions ◽  
Comfort Level ◽  
System Description ◽  
Wide Range ◽  
System Components ◽  
Overall Performance ◽  
And Performance

The objective of the system is to control the car heater temperature to ensure an optimum comfort level, without the need for periodic adjustment, despite variations in ambient temperature and vehicle usage. Reasons for choosing a particular type of system are explained. The operation is analysed, and expressed in terms of an equation. Difficulties in solution due to non-linear terms are overcome with the aid of a digital computer. Test data on the system components and vehicle characteristics are used in the computer program to obtain a prediction of the accuracy of temperature control over a wide range of operating conditions. Predicted performance is compared with actual road tests results for an installation. Design optimization is facilitated by using the computer to examine the effect of system parameter changes on the overall performance.

Modeling and control of heat pump system for battery electric buses

2022 ◽  
pp. 095440702110694
Author(s):  
Rabih Al Haddad ◽  
Hussein Basma ◽  
Charbel Mansour
Keyword(s):  
Energy Consumption ◽  
Weather Conditions ◽  
Heat Pumps ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Cold Weather ◽  
Pump System ◽  
Heat Pump System ◽  
Battery Capacity ◽  
Driving Range

Given the continuous tightening of emissions regulations on vehicles, battery-electric buses (BEB) play an essential role in the transition toward cleaner transport technologies, as they represent the most promising solution to replace diesel buses and reduce their environmental impact in the short term. However, heating the bus cabin leads to a considerable increase in energy consumption under cold weather conditions, which significantly reduces the driving range, given the limited battery capacity. Heat pumps (HP) are the primary heating technology used in BEB for their improved consumption performance compared to other technologies. Therefore, this study aims at optimizing the coefficient of performance (COP) of an HP system in a BEB for maximizing the bus electric driving range under cold weather conditions while maintaining satisfactory thermal comfort levels for passengers. Accordingly, an HP model is developed and integrated into an electric bus model using Dymola. A genetic algorithm (GA) based controller is proposed to find the optimal combination of the HP operating parameters, namely the compressor speed, the air mass flow rate at the inlet of the condenser, and the recirculation rate in order to maximize the system’s COP, and extend the BEB driving at different external temperatures, and as a function of the passengers’ occupancy levels. Results are carried under transient and steady-state operating conditions and show that the proposed GA-based controller saves up to 39% of the HP energy consumption as compared to the conventional HP control strategy, and therefore, enhances the BEB driving range up to 17%.

scholarly journals Blockchain Consensus: An Overview of Alternative Protocols

Symmetry ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1363
Author(s):  
Damilare Peter Oyinloye ◽  
Je Sen Teh ◽  
Norziana Jamil ◽  
Moatsum Alawida
Keyword(s):  
Energy Consumption ◽  
State Of The Art ◽  
Hash Functions ◽  
The State ◽  
Design Features ◽  
The Past ◽  
Trade Offs ◽  
Overall Performance ◽  
And Performance ◽  
Made In

Blockchain networks are based on cryptographic notions that include asymmetric-key encryption, hash functions and consensus protocols. Despite their popularity, mainstream protocols, such as Proof of Work or Proof of Stake still have drawbacks. Efforts to enhance these protocols led to the birth of alternative consensus protocols, catering to specific areas, such as medicine or transportation. These protocols remain relatively unknown despite having unique merits worth investigating. Although past reviews have been published on popular blockchain consensus protocols, they do not include most of these lesser-known protocols. Highlighting these alternative consensus protocols contributes toward the advancement of the state of the art, as they have design features that may be useful to academics, blockchain practitioners and researchers. In this paper, we bridge this gap by providing an overview of alternative consensus protocols proposed within the past 3 years. We evaluate their overall performance based on metrics such as throughput, scalability, security, energy consumption, and finality. In our review, we examine the trade-offs that these consensus protocols have made in their attempts to optimize scalability and performance. To the best of our knowledge, this is the first paper that focuses on these alternative protocols, highlighting their unique features that can be used to develop future consensus protocols.

scholarly journals The Factors Affecting Overall Performance in Japanese Firms: An Analysis among Environment, Strategy, Structure and Performance

2010 ◽  
Vol 11 (2) ◽  
pp. 55-75
Author(s):  
In Woo Jun
Keyword(s):  
Organizational Structure ◽  
Competitive Strategy ◽  
Business Environment ◽  
Competitive Strategies ◽  
Factors Affecting ◽  
Overall Performance ◽  
And Performance ◽  
Generic Strategies ◽  
Essential Prerequisite ◽  
Original Approach

This Study examined factors affecting overall performance in Japanese trading conglomerates by analysing the relationships among business environment, competitive strategy. organizational structure, and performance. As in the previous literature. this research also found that a form’s performance is not determined by a single factor, bur can be achieved through a combination of all elements such as strategy and organizational structure. However, contrary to our general understanding, one notable finding is that the environmental variables are not deemed as main obstacles for Japanese trading firms that hinder their overall performance. Although in the past, environmental uncertainty and complexity were regarded as a barrier char had to be overcome, they seem to be considered an essential prerequisite for Japanese trading conglomerates to attain their goals at present. This study also investigated the competitive strategy which Japanese trading firms are pursuing at this moment. Against Porter’s original approach, they can in some cases adopt more than one strategy at a rime from the generic strategies. This implies that Japanese trading firms may not create and sustain competitive advantage with a single specific strategy in today’s highly competitive business environment. For this reason, they mix two or more competitive strategies at once in order to respond against a highly competitive business environment.

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