Energy efficient management system of hot water-supply (HWS) of the educational block uses solar collectors as part of interactive educational laboratories.
Based on the distributive demonstration zone, a regional interuniversity energy conservation of BSTU has been adapted for use in educational process, energy efficient management system of hot water-supply (HWS) of the educational blocks using solar collectors as part of interactive educational laboratories has been created. The concept of virtual laboratory installation assumes in the remote access possibility to parameters and technological values of management system, including their change and regulation, access to archives data of parameters.
The cold water flowing into the system (fig.1) goes through the heat exchangers of traditional system of preparation of HWS which undergoes preliminary heating in the solar power device which is provided by two boilers (boiler 1 and 2) and solar collectors (fig.1). The water volume passing through the solar power device is defined by position of the dampfer of the electromechanical valve "Summer/winter Mode" depending on the amount of heat generated by the collectors. The use of the solar power device as part of the management system of hot water-supply (HWS) which allows the increment the system effectiveness of HWS in general due to decrease of energy spent for heating the heat carrier.
The use at the "lower level" of PLC of Segnetics SMH-2G with the Ethernet-module provides interchange data with "higher level" of management system by means of local area network of the university according to the MODBUS TCP/IP protocol.
The "higher level" of laboratory installation is provided by the dedicated server with a series of applications providing remote access through WEB (fig.2).
The interaction of laboratory installation happens by means of Web browser of the user (fig.2) that considerably allows lowering requirements to the remote workstation.
Thus, in the web browser, the user client implements the following functions:
1) installation supervision by means of the appropriate buttons of the user interface;
2) display of input and output signals by means of diagrams of trends temperatures and tip and information about t he current sensors status and function mechanisms.
The application of the mentioned concept allows the construction of a strong base for the virtual laboratories with remote access. Such approaches will considerably cut educational institution expenditures for the acquisition and service of very expensive laboratory equipment and will allow the construction of large-scale complex for practical skills in different science and branch directions.
The use of solar energy for heat supply is one of the most perspective directions of renewable usage (RU). Solar water-heating installations have the smallest turn-over periods from all types of RUS. They are technically simple to use and provide good ecological indices. Under these conditions, the deficit of energy carriers and their constant increase price, therefore the role of using alternative energy sources systems increases.
In the diagram the average data obtained from solar energy is shown in fig.3, it can be seen that the Belgorod region is located in the region where 1m2 (square meter) has 3 to 4 kW • hour of solar energy a day; duration of sunshine is also relatively high in comparison with other regions (fig.4).
From the analysis results the solar power plant functioning as part of HWS management system (fig.4), it is possible to conclude that the use is expedient during the period from the middle of April to the middle of October when average daily air temperature does not fall below 14ºС (temperature of cold water). Analyzing the change of heating power (fig.6), it is possible to conclude that the greatest efficiency is reached during the summer period of the year.
It is necessary to consider in more details changes of technological values during the effective solar collectors’ functions, i.e. the conservation time of year is during daylight.
The greatest interest, from the technological parameters point of view, represents the period of the most effective functioning of heliocollectors which is in details figured on a graphics (fig.7).
According to the statistical data obtained in the solar power device uses the schedules displaying overall performance of system in general have been demonstrated.
Fig.7. Temporary temperature charts of operation of the solar power device (where Txvs is temperature of cold water supply, Tgu is temperature at the solar power device exit. That is the temperature of antifreeze, Tb is temperature of the boiler, Tnv is temperature of external air)
The colored areas on diagram indicate provisional time schedules within a day: lunch, evening, night, morning. In the analysis of the above-stated statistical data, the following features of work system in general are revealed:
- during work at night the volume used is constant. As sunlight is absent, the helio-collector temperature moves towards the external air temperature, i.e. there is a cooling of the heliosystem heat carrier. Due to the continuous recirculation of the cooling-down antifreeze system, water temperature in the boilers of heliosystem decreases;
- in the morning when water supply system to the clients resumes (i.e., the beginning of its operation by consumers) temperature of HWS falls, along with it and the heat carrier temperature owing to heating of solar collectors which gradually increases in the sunlight intensity.
- the maximum solar activity is observed. The temperature of heliocollectors is maximum. There is a gradual water heating in the solar power device boilers which in connection with lag effect of process reaches the maximum level at about 17:00 hours.
An example of work of solar collectors system on September 6, 2011 at 16:00 is shown in fig.8 in the screen form of the automated workplace of the dispatcher. The key parameters of hot water supply (HWS) flowing is seen by the operator in real time.
The temperature of cold water flowing from city water supply is 17.82 °C and the heat from solar collectors allows the water temperature to increase to 36 °C, raising the temperature by 18 °C as in this case, provision of comfortable hot water requires temperature of 50-52°C, water heats up by 14°C and gets to consumers.
Thus, at the moment 56% of thermal energy for preparation of hot water comes from heliosystem.
The current daily consumption is 5.08 cubic metres of water, subsequently saving 90 000 kilocalories or 100 KWh of electrical energy which should be consumed when using electrical boilers. For 5 months with sufficient level of solar radiation of collectors and sufficient air temperature (May, June, July, August, September), subsequently the possible effective operation is 150 days with result in 13.5 Gcal of thermal energy or 15 000 kWh electrical energy. Thus the feasibility application of solar collectors with a total area of 24m2 (sq.m) as part of the solar power device of container storage volume of 4000 l is justified with daily average hot water consumption of 5-8 cubic metres.
The application of helio-collectors as part of the power supply system of BSTU allows not only to follow the modern concept of energy efficiency, but also to construct a powerful demonstration zone for obtaining practical skills in technical disciplines. The solar power plant is part of a centre of the BSTU virtual laboratories
Project Authors:
- Belousov A.V. (PhD) (Tech.Sci.) – Associate professor of Cybernetics Engineering, Head Department of Information and Communications.
- Koshlich Yu. A. – Graduate student Department of Cybernetics Engineering, Engineer of Information Management and Communications
- Moskovchenko S.I. – Engineer of Information Management and Communications.
Detailed information: http://ntk.intbel.ru