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Nestrugina OlgaPhysical and Metallurgical FacultyDepartment of industrial heat-and-power engineeringSpeciality: Energy managementTheme of master's work:Rationale for the possibilities of using pipes made of polymeric materials to increase energy efficiency of heating networksSupervisor: docent, c.t.s. Gridin S.V. |
Materials on the theme of master's work: About author |Curriculum vitae
Abstract on the Topic of Master's Work:
Relevance of the Work
The question of energy savings is very actual on the present time, it applies
to hot water, too. The pipes used for hot water supply in Ukraine at present, contribute to loss
a lot of heat on the way to the consumer (13%).
The use of pipes made of polymeric materials is widespread,
both in Europe and in Ukraine, and has an impressive growth. These materials have indisputable advantages
to metal pipes - no insulation, corrosion phenomena, large bandwidth,
light weight, sound insulation, lack of overgrowing microbial, resistance to corrosive substances
durability, ease of installation, etc. In the water supply they also increasingly use tubes made of polymers as an alternative
pipes of metal, not differing durability.
The possible materials for the replacement of existing pipes, options
isolated are regarded in the work and the best way justified on the basis of calculations is selected.
Aims and Objectives of the Research
The purpose of this study is to find and research options for replacing heat pipes
networks of polymeric materials, as well as improving energy efficiency of heating systems.
To achieve this objective the following tasks and solved:
- investigation and calculation of currently used metal pipes;
- investigation and calculation of the existing alternatives, but under-utilized at present in Ukraine;
- study of mathematical models of the production of pipes made ??of polymeric materials;
- development of a complex of guidelines and practical suggestions for the design of thermal circuits for the conditions of Ukraine.
Subject of study - a system of criteria, conditions and indicators, a methodology allowing
to determine the efficiency of heating systems and develop recommendations to improve them by using different
variants of pipes, to increase the reliability and safety of heat supply, environmental improvement, etc.
Methods of research include the creation of mathematical models, comparative analysis, numerical methods,
economic analysis.
The Scientific Novelty
The scientific novelty of the recent and planned research work is expected to:
- detailed study of polymeric materials to replace the pipes of heating systems;
- improve energy efficiency of thermal networks through the use of pipes of new alternative materials;
- development of a complex of guidelines and practical suggestions for the design of thermal circuits for the conditions of Ukraine.
Solving these problems is a real contribution to solving the problems of energy conservation and savings of energy resources in power engineering, industry and utilities in Ukraine.
Description of the Results
Currently, the hot water pipes use the following options:
- Metal pipes
- Tubes of glass
- polyethylene pipes
- Pipes of Polypropylene
- Pipes Polyvinyl Chloride
- metal pipe insulation with rigid polyurethane foam
When comparing the pipes of polymeric materials we can identify following:
- GRP pipes have a maximum resistance to temperature stress and minimal linear extension, so they are the most circulated in the heating systems. High elasticity of fiberglass pipes makes them easy to bend, and the aluminum layer remains shape attached to trumpet . This ensures in many cases a more simple and economical installation and maintenance of their health while in service;
- The advantages of plastic pipe is a high thermal stability (self-ignition temperature 415 ° C). This ensures their widespread use for heating systems, low hydraulic losses, high resistance connections. A polyethylene pipe without reinforcing layer have a high thermal expansion, therefore, usually used to flush;
- polypropylene pipes are less thermostable than metal-and plastic, so their primary use is hot and cold water; usage in heating systems is limited. Due to the high fluidity polypropylene tubes change over time, even under the influence own weight, so when external wiring pipes must be secured every 50 - 60 cm polypropylene pipe connection technology provides high bond strength is comparable to the strength of the pipe itself.
Consider the advantages and disadvantages of modern pipes for heating and water supply are considered below.
Fiberglass pipes are plastic pipes, with the base of their walls made of fiberglass and filler of
GRP pipe is epoxy or polyester resin. The advantages of GRP pipes:
- absence of corrosive particles in a stream are safe for health;
- high resistance to corrosion and chemically aggressive environments;
- GRP pipes are resistant to abrasion;
- high environmental and sanitary characteristics;
- sediments on the inner walls of pipes throughout the term of usage are virtually eliminated;
- the pipe material is eco-friendly, tightness of their connection eliminates a leakage of the transported fluid and contamination by groundwaters.
Pipes made ??of glass have also a number of drawbacks, most significant among which are hygroscopic and
water absorption, which significantly reduces their efficiency and lack of resistance to abrasion fiberglass, which causes wear and tear
inner layer of resin, the appearance of bare glass. The substances harmful to health may come into the stream of water (under pressure).
Трубы из полиэтилена имеют все достоинства труб на основе полимеров:
- high strength;
- high heat resistance, such pipes can be used at operating temperatures up to 90 °C. The polyethylene pipes at high temperatures do not "flow" and retain their shape;
- have high chemical resistance, they do not corrode;
- do not subject to fouling and fouling of salt;
- environmentally friendly;
- lifetime of polyethylene pipes is more than 50 years.
The material is included in the list with positive environmental characteristics. No toxic emissions. Has
international environmental certification ISO 14001. Applies even at pharmaceutical industry.
Disadvantage: the working temperature range of pipes are environmentally friendly, but when
the temperatures are above the melting point of polyethylenebut carbon monoxide, formaldehyde, acetic acid, aldehyde allocation is possible;
when silane method of production a saturated solution of silane in contact with tin alloys produces methanol. Methanol is a poison that effects
the nervous and circulatory systems, has the ability to accumulate in the body. Maximum allowable concentration of methanol in the air is 5 mg/m3.
The most mild form of poisoning is characterized by headaches, general weakness, malaise, chills, nausea, vomiting. Therefore,
dangerous to life, either methanol or liquids that contain this poison, even in relatively small quantities are dangerous to life.
Polypropylene pipes have a large number of advantages:
- ecological safety;
- the life of polypropylene pipes is more than 50 years;
- does not harm the environment. Nothing to do neither with his treatment, nor in the disposal of waste environmentally harmful substances are not produced. In addition, polypropylene is suitable for disposal without the addition of environmentally harmful substances.
- is absolutely safe to temperature range 120 °C, no allocates, can't be destroyed with chemicals, does not cause allergies, does not absorb odors, he doesn't smell, the service term is eternal.
Disadvantage: in case of fire almost doesn't burn , but it emits toxic fumes, although it is much
safer than polyethylene and polyvinyl chloride.
PVC pipes are environmentally friendly, but can not withstand the requirements for resistance to the possible
emergency and fire, because it is a flammable material which, when combustion emits toxic fumes oxides and dioxides.
Polyvinyl chloride is the cheapest form of plastic, but also the least environmentally friendly. It consists of chlorine, and when heated can release
phosgene gas, a substance that has a suffocating effect. Lethal concentration of 0,01 - 0,03 mg / l.
| The Pipe Properties | Pipe variants | |||
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| Steel | GRP | polyethylene | polyurethane | |
| Maximum operating temperature,°С | 450-550 | 1300-1350 | 95 | 160 |
| Density, kg/m3 | 7700-7900 | 1800-2000 | 910-960 | 40-70 |
| Thermal conductivity, W/m K | 64 | 0,75 | 0,36-0,43 | 0,03 |
| Cost, UAH/m | 159 | 796 | 170,64 | 15,26 |
| Lifetime, years | 10-25 | >50 | 50 | 25-30 |
For clarity and ease of comparison between the material shows histograms for all types of pipe characteristics are shown (Picture 1a-d):
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| Picture - Histograms of the tubes' properties |
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The payback period for one running meter:
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where C - the cost of the event, UAH; T - tariff for hot water, in Donetsk is
17.58 grn/m3; E - energy savings,%.
Steel pipes:
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GRP:
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Polyethylene:
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Polyurethane:
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Conclusion
We can conclude that the best material for replacement - GRP, it is environmentally safe, has the highest operating temperature, the longest service life, though, it is the most expensive material having the greatest payback.
Important Note
The Master's work is not completed yet. Final Completion: December 2011. A full text of the work and materials on the subject can be received from the author or his superviser after that date.