Summary
The ongoing implementation of new automatic heating substations in the apartments houses and installation of regulating valves on the individual room radiators cause substantial variations of the domestic heat consumption.
The aim of the case study is to increase efficiency of the HP "Zemliane", through saving electrical energy, consumed by the main heating network pumps, regulating their flows, respectively heating energy, by variable speed converters (VSC). The case study was financed by the Sofia Municipality as part of the Municipality share for founding SOFENA under the SAVE II project in 2001. In the development of the project experts from HP "Zemliane" and two professors form Technical University of Sofia took part.
Results
For the purpose of the model evaluation, the following table presents a comparison of the total heating water flow and the heat energy consumption values from real measurements, without pumps speed regulation, and those calculated by the model, with pumps speed regulation.
| No | TYPICAL DAY | Average hot water flow, t/h | Average hourly heat energy consumption, MWh | ||||
| Measured | Model | Relative difference, % | Measured | Model | Relative difference, % | ||
| 1 | Cold winter | 9925,8 | 9344,0 | 5,9 | 337,6 | 319,3 | 5,4 |
| 2 | Hot winter | 9987,8 | 9024,2 | 9,6 | 170,9 | 225,2 | -24,1 |
| 3 | Summer | 3637,6 | 3095,0 | 14,9 | 40,8 | 52,8 | -22,8 |
During the real measurements, throttling valves regulated the hot water flow. As could be seen, the coincidence of the flow values from the real measurements and the model is very close, but the modeled values of the heating energy is overestimated by the model for hot winter and summer days. The model values for the heating energy are greater because during the simulation experiments we tried to meet as close as possible the requirements for the consumers' comfort.
Note: The heating energy during summer is for domestic hot water only.
The next table presents a comparison between pumps' electricity consumption without speed regulation (100%) and with speed regulation. Further, the expected savings are calculated. As could be seen, considerable savings are expected, especially during summer days.
| No | TYPICAL DAY | Pumps daily electricity consumption, MWh | |||
| Pumps speed 100% | Pumps speed regulated. | Savings | |||
| MWh | % | ||||
| 1 | Cold winter | 138,776 | 120,869 | 17,907 | 12,90 |
| 2 | Hot winter | 143,288 | 111,239 | 32,049 | 22,37 |
| 3 | Summer | 71,440 | 37,133 | 34,307 | 48,02 |
From statistics we have the following figures for the number of the three types of days:
The expected savings due to the pumps' regulation are:
| For the cold winter days: | 41 days x 17,907 MWh | = | 734,187 MWh | |
| For the hot winter day: | 124 days x 32,049 MWh | = | 3 974,076 MWh | |
| For the summer days: | 200 days x 34,307 MWh | = | 6 861,400 MWh | |
| TOTAL | 11 569,663 MWh |
To find similar reports, click on a keyword below:
District Heating
: Energy Efficiency
: Heat/Heating
: Households
: Industry
: ManagEnergy
: Refurbishment of Buildings
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Case Study (123 KB PDF)