Master's Portal|
DonNTU|
Yandex|
| |
|
|
|
|
Master's Portal| |
|
DonNTU| |
|
Yandex| |
|
||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
 |
 |
 |
|---|
 |
Tatyana VeretennikovaPhysical-and-Metallurgical Dept Field of Study – Energy Management Topic of Master’s Thesis: « The Investigation of a Heat-and-Power Supply Source Scheme with a Load Controlling by Means of Heat Pumps with the Object to Improve an Efficiency of a Primary Rnergy Recourses Use » |
Actuality of WorkProblem Development Stage and Unsolved QuestionsA task of reduce of primary energy resources consumption in the fuel and energy complex of any country has always been very actual. Especially it is for Ukraine, as the state, being only partly provided with the traditional types of primary energy resources, and forced to import them. This situation is aggravated also by high power consumption of manufacture, bad state and acquisition of energygenerating productions and energydistributing systems, by the considerable sizes of non-payments from the side of consumers, gas economy lack of the country, etc. We also have to take into account that principles of the heat supply systems design, used in soviet time, became antiquated.Therefore the basic steps of Ukraine to overcome all foregoing problems must be directed to the energy-saving and increase of the heat supply systems energy efficiency. It is connected with the development of new methods, criteria, terms and indexes, allowing to determine the optimal chart during the reconstruction of old or design of new heat supply systems for a concrete consumer. Here we need the system approach taking into account the features of climate conditions, descriptions and properties of consumer, presence of perspective renewal energy recourses, etc.In particular in this thesis it is examined possibility of the cogeneration plants application as a source of heat-and-power supply as one of methods to increase the thermal energy production efficiency, which can give considerable fuel economy up to 40%. It is actual, especially, whereas, the modern world tendency is a transition from centralized to distributed mini- micro- generation, maximally closed to the final consumer.The chart of the heat-pump unit use of different types in a thermal chart of mini cogeneration power plant is developed. This chart has to execute the task of thermal and electric energy relative production controlling. The methods of thermal chart working indexes determination are also developed depending on equipment parameters, operation schedules and load controlling.Problems: criteria and analytical expressions for design of concrete set (capacities, executable loading, operation schedules, etc.) will be on the basis of are developed.The general object of this work is to increase the efficiency of the primary energy recourses use in the systems of thermal and electric energy generation, and also to increase a power safety, to improve an ecological situation.For achievement of the indicated purpose in the thesis the next tasks are put and soluted:
The subject of investigation is the set of criteria, terms and indexes, and also methodology, allowing to determine efficiency of the heat supply systems and develop recommendations on their improvement with the use of cogeneration and other alternative technologies, with the purpose of fuel resources consumption reduce, increase of reliability and safety of heat supply, improvement of the environment state, etc.Research methods include creation of mathematical models, comparative analysis of results, numeral methods, thermodynamics analysis, economic analysis.The scientific novelty of the researches already conducted and planned is assumed in the following:In the chart of heat-and-power supply source a heat-pump is an element, allowing to regulate correlation of thermal and electric energy production. Taking into account the different costs of power in a different daypart, a heat-pump allows optimizing the mode of cogeneration power plant operations with the purpose of receipt of maximal profit. The principal chart that including heat pump and cogeneration units is shown on a figure 1.
The heat pump unit (HPU) is the first stage of water heating. It is connected with the fact that operation efficiency of HPU is proportional to temperature difference between the low-grade heat source and heat-carrier. Heat-pump, cooling a low temperature thermal energy source from tи1 to tи2, heats water from 
to 
. Further water enters cogeneration unit (CU), where it heated to the temperature 
. Let’s exam a variant with compression heat-pumps, because we need for their driving the electric power, produced by CU. Most compression heat-pumps, depending on the type of the applied operation medium, have limitation of maximal water heating temperature of 55-65 °С.Share of heating load 
, which heat-pumps will carry in the examined chart on condition that all electric power, produced by CU, will be consumed by the drive of HPU, taking into account the own needs of cogeneration power plant (CPP), will define on a formula:
(1)
The water temperature after a heat-pump will be determined on the basis of temperature chart and share of heating load, executed by heat-pumps:
(2)
Then the estimated share of HPU heating load coverage will be equal:
(3)
Temperature controlling we will carry out, comparing two values - α and α', i. e. by comparison of heating load share which a heat-pump will cover at current conditions, and maximum heating load share which can cover HPU taking into account limitation of .Comparing these values, we can estimate general operation efficiency of CPP. Now let’s exam the possible cases of their correlation.
: there is not surplus of power producing, i. e. all power, produced by CU goes to the driving of HPU.
: there is surplus of power producing. In this case it is necessary to take into account whether there is a hard condition on delivery of electric power in a grid:Thus the first case is more unprofitable, especially under condition of possibility to get a profit from the power sale in the second one.Delivery of surplus produced power in a grid it is expedient to carry out in a peak period covering the failing load from ineffective sources, when it needs to the grid. I. e. we don’t create a disbalance in it. Thus HPU disconnect through a bypass, increasing the power amount given in a grid, and all heating load is carried by CU. It can be economic justified in a semi-peak period too.Consequently the positive role of such operation controlling of this chart is obvious.Pluses of the chart:Minuses:In the thesis it is analyzed possible methods of electric and thermal powers production correlation controlling at CPP. It is shown that most effective, from position of fuel expense, there is the use of heat-pumps in the thermal chart. New analytical expressions for determination of fuel consumption are offered at a thermal and electric energies production in the combined cycle, taking into account operation schedules and CPP load controlling.Investigations of thermal charts and CPP operation indexes with the use of heat-pumps at implementation of the different thermal loadings are conducted. Appropriate design methods are offered.On the basis of the conducted investigations it is offered the design method of heat-and-power supply source taking into account the alternative variants of thermal charts which can be realized for a consumer.The developed methods allow: