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District Heating for Residential Areas with Single-Family Housing -with Special Emphasis on Domestic Hot Water Comfort

Persson, Tommy LU (2005)
Abstract (Swedish)
Popular Abstract in Swedish

Konceptet fjärrvärme inbegriper central värmeproduktion från vilken värme distribueras ut till de enskilda förbrukarna via ett rörsystem. Ett grundläggande krav, med hänsyn till fjärrvärmens konkurrenskraft, är att vinsten som görs i den storskaliga värmeproduktionen, jämfört med lokal värmeproduktion, överstiger kostnaderna för värmedistributionen. Distributionskostnaderna per levererad kWh ökar desto lägre värmetätheten i ett område är, detta innebär att den potentiella konkurrensfördelen för fjärrvärme normalt är större i områden med t.ex. flerfamiljshus än i småhusområden. Trots detta faktum har de svenska fjärrvärmebolagens intresse för expansion i småhusområden ökat under de senaste åren.... (More)
Popular Abstract in Swedish

Konceptet fjärrvärme inbegriper central värmeproduktion från vilken värme distribueras ut till de enskilda förbrukarna via ett rörsystem. Ett grundläggande krav, med hänsyn till fjärrvärmens konkurrenskraft, är att vinsten som görs i den storskaliga värmeproduktionen, jämfört med lokal värmeproduktion, överstiger kostnaderna för värmedistributionen. Distributionskostnaderna per levererad kWh ökar desto lägre värmetätheten i ett område är, detta innebär att den potentiella konkurrensfördelen för fjärrvärme normalt är större i områden med t.ex. flerfamiljshus än i småhusområden. Trots detta faktum har de svenska fjärrvärmebolagens intresse för expansion i småhusområden ökat under de senaste åren. Detta är bland annat en följd av den redan höga marknadsandelen i områden med hög värmetäthet, större ekonomiska incitament för att investera i kombinerad värme- och kraftproduktion samt av insikten att fjärrvärme kan bidra till ett uppfyllande av de svenska åtagandena enligt Kyoto Protokollet.



Denna avhandling fokuserar på fjärrvärme i småhusområden med särskilt fokus på tappvarmvattenkomfort. Det sistnämnda kan ibland vara svårt att säkerställa under tider på året när det ej råder uppvärmningsbehov. Undersökningarna är huvudsakligen teoretiska och framförallt baserade på dynamiska simuleringar och finita element beräkningar. Laboratorieprovningar, fältmätningar samt enkäter riktade till fjärrvärmebolag användes i viss omfattning för att empiriskt verifiera resultaten samt för att ge en praktisk tolkning av dem. Fyra vanligt förekommande problem i fjärvärmesystem i småhusområden är: dålig avkylning av fjärrvärmevattnet, höga specifika värmeförluster, otillfredsställande tappvarmvattenkomfort sommartid samt höga specifika investeringskostnader. Samtliga dessa ämnen behandlas, direkt eller indirekt, i detta arbete.



Vid modellering av konventionella fjärrvärmesystem studeras i avhandlingen moderna 2-rörssystem med indirekt anslutning av de husinterna uppvärmningssystemen och tappvarmvattenberedning av genomströmningstyp. Bland annat följande ämnen studeras: termostatiska ventiler för säkerställande av en acceptabel framledningstemperatur sommartid, design och funktion av tappvarmvattenregulatorer samt dimensionering av fjärrvärmerör. Vidare identifieras t.ex. önskvärda egenskaper för termostatiska ventiler och deras inverkan på temperaturnivån i husinterna tappvarmvattensystem. Baserat på en teoretisk modell av bakterietillväxt, uppskattas även omfattningen av tillväxt i ett tappvarmvattensystem med bristfällig funktion. Vidare beräknas värmeförluster från en ny typ av fjärrvärmekulvert som har potential att reducera anläggningskostnader. Fjärrvärmekulverten består av ett 4-rörssystem med medierör av PEX (tvärbunden polyeten) inuti EPS (expanderad polystyren) block som fungerar både som isolering och som mekaniskt skydd av medierören. Beräkningar och fältmätningar visar att värmeförlusterna från EPS-PEX kulverten är ca hälften av dem från motsvarande 4-rörssystem bestående av två konventionella twinrör. I 4-rörssystem råder samma behov av tappvarmvattencirkulation som i husinterna tappvarmvattensystem i större fastigheter. I områden med låg värmetäthet är det nödvändigt med en hög marknadsandel för att i möjligaste mån undvika höga specifika investeringskostnader och värmeförluster. Med detta i åtanke genomfördes en enkätundersökning bland ett stort antal fjärrvärmeföretag för att identifiera marknadsstrategier som idag används i småhusområden. Ett huvudresultat från undersökningen var att företagen generellt sett har bristande information om inkomst, ålder och andra sociala faktorer om de potentiella kunderna. Sådan information kan utgöra en grund för att bedöma kundernas preferenser och skulle därmed kunna bidra till utvecklandet av effektivare marknadsföringsmetoder. (Less)
Abstract
The concept of district heating (DH) involves centralised heat production where heat is distributed to consumers via a piping network. It is essential that benefits achieved from concentrated, large-scale production instead of local production in each building exceed the costs associated with heat distribution. Since the distribution cost per delivered kWh increases as the heat density of an area decreases, the possible competitive advantage of DH will be greater in areas with multi-family housing than in residential districts dominated by single-family dwellings. Nevertheless, in the last few years there has been a growing interest among Swedish DH companies in expansion into low heat density areas. This is a consequence of an already... (More)
The concept of district heating (DH) involves centralised heat production where heat is distributed to consumers via a piping network. It is essential that benefits achieved from concentrated, large-scale production instead of local production in each building exceed the costs associated with heat distribution. Since the distribution cost per delivered kWh increases as the heat density of an area decreases, the possible competitive advantage of DH will be greater in areas with multi-family housing than in residential districts dominated by single-family dwellings. Nevertheless, in the last few years there has been a growing interest among Swedish DH companies in expansion into low heat density areas. This is a consequence of an already large market share in high heat density areas, increasing economic incentives to invest in combined heat and power production, and an understanding that DH can play an important role in fulfilling political ambitions for Sweden to comply with the obligations according to the Kyoto Protocol.



This thesis focuses on DH in residential areas with single-family housing with particular emphasis on domestic hot water (DHW) comfort, which can sometimes be problematic in the non-heating season. The investigations are mainly based on theoretical findings achieved by performing dynamic simulations and finite element calculations. Laboratory measurements, field experimentation and questionnaires posed to operating companies were used to provide in part empirical verification, as well as a framework for practical engineering interpretation. Four recurrent problems in DH systems in single-family housing areas are: low primary water cooling, high specific heat losses, unsatisfactory DHW comfort during summertime, and high specific installation costs. All these topics are examined in this work, either directly or indirectly.



State-of-the-art 2-pipe systems with indirect connection of space heating systems and instantaneous hot water heaters were assumed when modelling conventional systems. For the following topics numerical results were derived: thermostatic valves for securing an acceptable DH supply temperature during summertime, design and functioning of DHW controllers, and sizing of DH pipelines. Desirable characteristics of thermostatic valves and their influence on the temperature level in a DHW system were identified. Based on a numerical model of positive or negative bacterial growth, predictions were made of extent of growth in faulty DHW systems. Heat losses were calculated for a novel type of DH piping arrangement that has the potential to reduce investment costs. The system studied is a 4-pipe system with carrier pipes made of PEX (cross-linked polyethylene), arranged with EPS (expanded polystyrene) blocks that provide both heat insulation and mechanical protection. Calculations and field measurements show that the heat losses from the EPS-PEX culvert studied are approximately half those of a corresponding 4-pipe system consisting of two conventional twin pipes. For 4-pipe system networks, temperature problems similar to the ones experienced when employing DHW re-circulation in residential buildings were studied. In areas of low heat density, it is imperative that a high degree of market penetration is achieved to avoid inordinately high specific investment costs and heat losses. With this objective in mind, a survey was carried out among a large number of DH companies to identify current marketing strategies. The main result was that companies generally posses too crude a knowledge of income, age and other sociological factors about their potential customers. Such information could provide a basis for making reasonable hypotheses about consumer preferences, to form a basis for making future marketing more effective. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Dr. Ing. Volla, Rune, Viken Fjernvarme A/S, Norway
organization
publishing date
type
Thesis
publication status
published
subject
keywords
low heat density, District heating, single-family housing, domestic hot water comfort, domestic hot water control, heat losses, supply temperature, thermostatic valves, Energiforskning, Energy research, marketing strategies, market penetration
pages
260 pages
publisher
Division of Energy Economics and Planning, Department of Heat and Power Engineering, Lund University
defense location
Room M:B of the M-building Lund Institute of Technology Lund, Sweden
defense date
2005-06-16 10:15
external identifiers
  • other:ISRN:LUTMDN/TMHP--05/1032--SE
ISSN
0282-1990
ISBN
91-628-6504-8
language
English
LU publication?
yes
id
27c83d56-28c9-4971-80c8-63dadb6db310 (old id 545111)
date added to LUP
2007-09-10 14:06:07
date last changed
2016-09-19 08:44:56
@phdthesis{27c83d56-28c9-4971-80c8-63dadb6db310,
  abstract     = {The concept of district heating (DH) involves centralised heat production where heat is distributed to consumers via a piping network. It is essential that benefits achieved from concentrated, large-scale production instead of local production in each building exceed the costs associated with heat distribution. Since the distribution cost per delivered kWh increases as the heat density of an area decreases, the possible competitive advantage of DH will be greater in areas with multi-family housing than in residential districts dominated by single-family dwellings. Nevertheless, in the last few years there has been a growing interest among Swedish DH companies in expansion into low heat density areas. This is a consequence of an already large market share in high heat density areas, increasing economic incentives to invest in combined heat and power production, and an understanding that DH can play an important role in fulfilling political ambitions for Sweden to comply with the obligations according to the Kyoto Protocol.<br/><br>
<br/><br>
This thesis focuses on DH in residential areas with single-family housing with particular emphasis on domestic hot water (DHW) comfort, which can sometimes be problematic in the non-heating season. The investigations are mainly based on theoretical findings achieved by performing dynamic simulations and finite element calculations. Laboratory measurements, field experimentation and questionnaires posed to operating companies were used to provide in part empirical verification, as well as a framework for practical engineering interpretation. Four recurrent problems in DH systems in single-family housing areas are: low primary water cooling, high specific heat losses, unsatisfactory DHW comfort during summertime, and high specific installation costs. All these topics are examined in this work, either directly or indirectly.<br/><br>
<br/><br>
State-of-the-art 2-pipe systems with indirect connection of space heating systems and instantaneous hot water heaters were assumed when modelling conventional systems. For the following topics numerical results were derived: thermostatic valves for securing an acceptable DH supply temperature during summertime, design and functioning of DHW controllers, and sizing of DH pipelines. Desirable characteristics of thermostatic valves and their influence on the temperature level in a DHW system were identified. Based on a numerical model of positive or negative bacterial growth, predictions were made of extent of growth in faulty DHW systems. Heat losses were calculated for a novel type of DH piping arrangement that has the potential to reduce investment costs. The system studied is a 4-pipe system with carrier pipes made of PEX (cross-linked polyethylene), arranged with EPS (expanded polystyrene) blocks that provide both heat insulation and mechanical protection. Calculations and field measurements show that the heat losses from the EPS-PEX culvert studied are approximately half those of a corresponding 4-pipe system consisting of two conventional twin pipes. For 4-pipe system networks, temperature problems similar to the ones experienced when employing DHW re-circulation in residential buildings were studied. In areas of low heat density, it is imperative that a high degree of market penetration is achieved to avoid inordinately high specific investment costs and heat losses. With this objective in mind, a survey was carried out among a large number of DH companies to identify current marketing strategies. The main result was that companies generally posses too crude a knowledge of income, age and other sociological factors about their potential customers. Such information could provide a basis for making reasonable hypotheses about consumer preferences, to form a basis for making future marketing more effective.},
  author       = {Persson, Tommy},
  isbn         = {91-628-6504-8},
  issn         = {0282-1990},
  keyword      = {low heat density,District heating,single-family housing,domestic hot water comfort,domestic hot water control,heat losses,supply temperature,thermostatic valves,Energiforskning,Energy research,marketing strategies,market penetration},
  language     = {eng},
  pages        = {260},
  publisher    = {Division of Energy Economics and Planning, Department of Heat and Power Engineering, Lund University},
  school       = {Lund University},
  title        = {District Heating for Residential Areas with Single-Family Housing -with Special Emphasis on Domestic Hot Water Comfort},
  year         = {2005},
}