12th International Symposium on District Heating and Cooling

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The <strong>12th</strong> <strong>International</strong> <strong>Symposium</strong> on District Heating and Cooling,September 5 th to September 7 th , 2010, Tallinn, Estoniatraditional systems. The flat station concept has a netenergy saving due to less installed hot pipes. Energysavings are in the range of 2 to 4 kWh/m^2/y for theinvestigated cases. Comfort level has beeninvestigated, revealing well acceptable dynamic controlperformance. Dhw temperature recovery after an idleperiod for the instantaneous preparation of dhw is,however, a trade-off between comfort and energysaving. Related to Legionella, then risk can be reducedwhen installing flat stations as presented in this paper.REFERENCES[1] Kristjansson, H. Comparing Distributions Systemsin Blocks of Flats, SDDE 2009, Slovenia[2] Gullev, L., Poulsen, M. ―The Installation of MetersLeads to Permanent Changes in ConsumerBehaviour‖, the magazine ―News from DBDH‖,#3/2006.[3] DS 452, Code of practise for thermal insulation oftechnical service and supply systems in buildings,2. Revision, Dansk Standard, 1999[4] Thorsen, J.E. Cost considerations on Storage Tankversus Heat exchanger for htw preparation, The10th <strong>International</strong> <strong>Symposium</strong> on District Heatingand Cooling 2006.[5] Thorsen, J. E. Control Concepts for DH CompactStations Investigated by Simulations, The 9th<strong>International</strong> <strong>Symposium</strong> on District Heating andCooling 2004.[6] http://www.danfoss.com/Products/Categories/List/HE/Temperature-Controllers/Temperature-controllers/IHPT-and-XB-06/b1c8a73c-59f1-4fef-8b52-f49c97b6019b.html[7] http://www.danfoss.com/Products/Categories/Group/HE/District-Heating-Substations/Substations-Direct-Heating/Flat-Stations/8f81605b-bab9-4644-961b-51a3f0503f05.html[8] DVGW regulations, Germany, Arbeitsblatt W551,April 2004[9] Olsen, P.K., Lambertsen, H., Hummelshøj, R.,Bøhm, B., Christiansen, C.H., Svendsen, S.,Larsen, C.T., Worm, J. A new Low-TemperatureDistrict Heating System for Low-Energy Buildings,The 11th <strong>International</strong> <strong>Symposium</strong> on DistrictHeating and Cooling 2008.[10] Paulsen, O., Jianhua, F., Furbo, S., Thorsen, J. E.Consumer Unit for Low Energy District Heating NetWorks. The 11th <strong>International</strong> <strong>Symposium</strong> onDistrict Heating and Cooling 2008.21
The <strong>12th</strong> <strong>International</strong> <strong>Symposium</strong> on District Heating and Cooling,September 5 th to September 7 th , 2010, Tallinn, EstoniaIMPROVED TEMPERATURE PERFORMANCE OF RADIATOR HEATING SYSTEMCONNECTED TO DISTRICT HEATING BY USING ADD-ON-FAN BLOWERSPer-Olof Johansson 1 , Janusz Wollerstrand 21 & 2Lund University, Department of Energy Sciences, Division for Efficient Energy SystemsCorresponding author: per-olof.johansson@energy.lth.se, Energy Sciences, Lund University, P.O. Box 118,221 00 Lund, Sweden, Phone: + 46 46 222 40 43, Fax: + 46 46 222 47 17ABSTRACTDistrict heating (DH), which is the most common heatsource in multifamily houses and commercial buildingsin Sweden, can be produced in several different type ofproduction units.In order to gain thermal efficiency in a DH system it isimportant that DH supply and return temperatures arekept low. The temperature demand in the DH system is,during the heating season, dependent on thetemperature level in the heating system of the DHconnected buildings. Many production units benefit froma lowered DH return temperature, while others are moreaffected by a reduced supply temperature. In a CHPstationthe heat to power ratio will increase when theDH supply temperature is decreasing. In order to reducethe temperature demand, low temperature heatingsystems are of interest, as well as systems resulting in alow DH return temperature.To increase the heat output in an existing radiatorheating system, the radiators can be complementedwith small electric fans resulting in an increased shareof forced convection in the heating system. Field studieshave shown that the heat output, with constant supplytemperature and mass flow through the radiator, canincrease with more than 50%.INTRODUCTIONFor many years, return temperatures in DH networkshave been an important issue for DH research. A lowDH return temperature is in many cases favorable forthe DH production units. However, if also the supplytemperature could be kept at a low level the share ofelectricity produced in a CHP station could increase.This would lead the way towards an increased share ofelectricity produced by non fossil fuels. In Sweden morethan 30 % of the DH is produced in CHP stations [4].In many reports the gain from a reduced temperaturelevel in the DH network has been discussed andquantified in economic terms, see e.g. [12], [13].The DH supply temperature level in the DH network is,during heating season, dependent of the temperaturedemand in the DH-connected buildings heating system.In modern buildings low temperature heating systemsare common, which may allow reduced DH temperaturelevel. In order to reduce the temperature demand inexisting buildings the idea of using small add-on-fanblowers placed under the radiator to increase the heatoutput due to an increased share of forced convectioncame up.ObjectiveThe field study presented in this paper investigates thepossibility to reduce the space heating temperatureprogram and estimates the impact on the DH supplyand return temperature. Possible reduction of the DHflowrate is also calculated.This paper is focusing on buildings indirectly connectedto the DH network through a substation with heatexchangers (HEX).DESCRIPTION OF ADD-ON-FAN BLOWERThe add-on-fan blower that is tested in this studyconsists of several regular DC motor driven fans,originally used for cooling, mounted under a radiator,see Fig. 1. In the study, two different kinds of radiatorswere tested, a panel and a column radiator.T ssSpace heatingradiatorAdd-on-fanT srIncreased air flowFloorm sOuter wallFig. 1 The add-on-fan blower mounted on a panel radiator.The add-on-fan blowers in this study are provided by aSwedish company: A-energi AB (the product is called―fläktelement‖ in Swedish). The company describes thefeatures of the add-on-fan blower as a possibility toreduce the temperature program without replacing theradiators, with the aim to reduce the electricity demandfor buildings supplied with heat from heat pumps [5].22
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to heating costs of 14,5 ct/kWh. Th
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academic access is facilitated as t
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1. CHP system operation in A2. Ther
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is covered by operating HOB. In oth
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produce heat and electricity. Fluct
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To assure that the temperatures mea
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production and provide for marginal
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In addition, it can also be observe
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Stockholm district heating system a
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The values presented do of course l
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12th International Symposium on District Heating and Cooling

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