Task 45
Task 45
SHC Task 45

Large Scale Solar Heating and Cooling Systems

Project (Task) Publications

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The following are publications developed under Task 45:

General Task Publications

Design Handbook Design Handbook
Installation, Commissioning and Operation of Large Scale Solar Thermal Plants
December 2012 - PDF 1.66MB - Posted: 2016-04-26
By: Anna Katharina Provasnek and Sabine Putz, S.O.L.I.D., Austria
This handbook aims to provide guidance in designing best practice, large-scale solar thermal systems, geothermal heat pump systems and hybrid district heating systems. It addresses common design issues, operation and financing issues. The final chapter gives examples for successfully constructed plants.

Subtasks

Subtask A: Collector Field and Loop

Requirements & guidelines for collector loop installation
IEA-SHC INFO SHEET 45.A.2
April 2015 - PDF 0.42MB - Posted: 2015-04-30
By: Samuel Knabl and Christian Fink (co-authors: Philip Ohnewein, Franz Mauthner, Robert Hausner)
The state of the art of hydraulics (collector and collector array hydraulics) and safety (including stagnation) aspects of the primary solar loop is presented and analysed in a theoretical as well as practical framework, also referring to examples of successfully implemented projects. It is based on international know-how collected by IEA networking activities, presented in a condensed form in this document.
Requirements & guidelines for collector loop installation
IEA-SHC TECH SHEET 45.A.2
April 2015 - PDF 1.96MB - Posted: 2015-04-30
By: Samuel Knabl and Christian Fink (co-authors: Philip Ohnewein, Franz Mauthner, Robert Hausner)
Large-scale solar thermal plants (gross collector area of more than 500 m² resp. 0.35 MWth) provide a huge potential for reducing the consumption of fossil fuels and CO2 emissions. Especially in the context of district heating, industrial processes and thermal cooling, large-scale solar thermal plants are becoming more and more important. Numerous projects in Europe (especially in Denmark) but also internationally (China, Canada, Saudi Arabia, etc.) constitute powerful examples for this trend. The implementation of solar thermal energy has already proved to be technically and economically feasible and sustainable in the practical context. However, the potential is still far from being exhausted.

This document focuses on the remaining practical challenges concerning the implementation of large-scale solar thermal plants. For this purpose, the state of the art of hydraulics (collector and collector array hydraulics) and safety (including stagnation) aspects of the primary solar loop is presented and analysed in a theoretical as well as practical framework, also referring to examples of successfully implemented projects. It is based on international know-how collected by IEA networking activities, presented in a condensed form in this document.
Simulation of large collector fields for system design and optimization
IEA-SHC TECH SHEET 45.A.4
February 2015 - PDF 0.46MB - Posted: 2015-02-19
Simulation is a very useful tool for design and sizing of a solar collector field. To get a good accuracy it is important to start with a load analysis and secondly to find accurate enough local weather data. Also a time resolution of at least hourly weather data is needed. The split into beam and diffuse radiation is also very important, to derive a good all-day simulation accuracy. Then of course the component models and accuracy of the input data is very important too. Below some hints are given to make a good collector field simulation.
Simulation of large collector fields for system design and optimization
IEA-SHC INFO SHEET 45.A.4
February 2015 - PDF 0.31MB - Posted: 2015-02-19
By: Bengt Perers and Simon Furbo
Simulation is a very useful tool for design and sizing of a solar collector field. To get a good accuracy it is important to start with a load analysis and secondly to find accurate enough local weather data. Also a time resolution of at least hourly weather data is needed. The split into beam and diffuse radiation is also very important, to derive a good all-day simulation accuracy. Then of course the component models and accuracy of the input data is very important too. Below some hints are given to make a good collector field simulation.
Correction of collector efficiency depending on fluid type, flow rate and collector tilt
IEA-SHC INFO SHEET 45.A.1
February 2015 - PDF 0.35MB - Posted: 2015-02-25
By: Federico Bava, Simon Furbo, Alfred Brunger
The efficiency of a solar collector is influenced by the solar collector fluid, flow rate and collector tilt. However, test institutes usually determine the collector efficiency for only one combination of fluid type, flow rate and tilt angle. This fact sheet describes investigations on the influence and importance of variations of solar collector fluid, flow rate and collector tilt on the efficiency and thermal performance of different solar collectors. Additionally, the effect of a fluorinated ethylene propylene foil used as convection barrier between glass cover and absorber is investigated.
Correction of collector efficiency depending on fluid type, flow rate and collector tilt
IEA-SHC TECH SHEET 45.A.1
February 2015 - PDF 0.82MB - Posted: 2015-02-25
By: Federico Bava, Simon Furbo, and Alfred Brunger
In its basic form, a solar thermal collector is designed to intercept solar radiation, absorb that radiation to convert it into heat energy, and then deliver that heat to a heat transfer fluid. Therefore, the performance of a solar thermal collector is influenced by all variables that affect either the optical or the thermal properties of the collector. For example, the incidence angle of solar radiation onto the solar collector can affect the optical performance of the collector. While typically not a strong factor for solar thermal collectors, the changing spectral quality of sunlight with changing atmospheric conditions can influence the fraction of the incoming solar radiation that gets transmitted and absorbed by the collector. Tilt angle, especially for glazed flat plate collectors, affects internal and external convective heat transfer coefficients, and thus influences collector thermal performance. Heat transfer fluid flow rate and fluid thermal properties influence the heat transfer coefficient inside the fluid passages of the collector, and thus influence the collector efficiency.
Guaranteed Power Output
IEA SHC INFO Sheet 45.A.3.2
April 2014 - PDF 0.32MB - Posted: 2014-04-11
By: Jan Erik Nielsen, PlanEnergi
The performance guarantees described here relate to the power performance of a collector field and a heat exchanger under some restricted (“full load”) operating conditions. The procedures described here do not pretend to give and check a guarantee on the annual output of the system. For annual output guarantee, see IEA-SHC Fact Sheet 45.A.3.2 “Guaranteed annual output”
Guaranteed Power Output Guaranteed Power Output
IEA SHC TECH Sheet 45.A.3.2 (R1)
March 2016 - PDF 0.73MB - Posted: 2016-04-08
By: Jan Erik Nielsen, PlanEnergi & Daniel Trier, PlanEnergi
The performance guarantees described here relate to the power performance of a collector field and a heat exchanger under some restricted (“full load”) operating conditions. The procedures described here do not pretend to give and check a guarantee on the annual output of the system.
Revised version (March 2016)
Guaranteed Power Output
IEA SHC TECH Sheet 45.A.3.2
April 2014 - PDF 0.62MB - Posted: 2014-04-11
By: Jan Erik Nielsen, PlanEnergi & Daniel Trier, PlanEnergi
The performance guarantees described here relate to the power performance of a collector field and a heat exchanger under some restricted (“full load”) operating conditions. The procedures described here do not pretend to give and check a guarantee on the annual output of the system.
Guarantee of Annual Output
IEA-SHC INFO Sheet 45.A.3.2
April 2014 - PDF 0.37MB - Posted: 2014-04-11
By: Jan Erik Nielsen, PlanEnergi
This method for giving and checking annual output of collector fields takes into account that the weather and operating temperatures may vary from year to year. The method works with monthly average operation temperatures and hourly average weather data and will work for systems having approx. constant operating temperatures on a monthly basis – like e.g. solar district heating systems. The basic idea of the method is described in brief below.
Guarantee of Annual Output
IEA SHC TECH Sheet 45.A.3.2
April 2014 - PDF 0.59MB - Posted: 2014-04-11
By: Jan Erik Nielsen, PlanEnergi
A methodology for giving and checking the annual output of collector fields is described. The method takes into account that the weather and operating temperatures may vary from year to year. The method works with monthly average operation temperatures and hourly average weather data and will work for systems having approx. constant operating temperatures on a monthly basis – like e.g. solar district heating systems.

Subtask B: Storage

Seasonal Thermal Energy Storage
Report on state of the art and necessary further R+D
June 2015 - PDF 11.43MB - Posted: 2016-04-08
By: Dick Mangold and Laure Deschaintre
Publisher: IEA Task 49
The technology of large scale seasonal thermal energy storage (STES) has been investigated in Europe since the middle of the 70's. First demonstration plants were realized in Sweden in 1978/79 based on results of a national research program.
Seasonal Borehole Thermal Energy Storage – Guidelines for Design & Construction
IEA-SHC INFO SHEET 45.B.3.1
February 2015 - PDF 0.24MB - Posted: 2015-02-19
By: Bruce Sibbitt and Doug McClenahan
Borehole thermal energy storage (BTES), which is also referred to as duct storage, has been successfully used for seasonal heat storage in a number of large solar systems. Some of these systems utilize a heat pump to upgrade the stored energy to the load temperature while others use the stored heat directly without upgrading. Borehole thermal energy storages have also been used for storing cold. BTES use the heat capacity in a large volume of native soil to store thermal energy underground. The soil itself is a very good medium for large heat storage systems since it is no-cost, already on-site, involves minimal excavation, is non-toxic and has a reasonable heat capacity. Much of the cost of a BTES is in the heat exchanger used to transfer heat to and from the soil, the drilling of boreholes in which to install the heat exchanger and in the insulation which is placed over the top of the store. For smaller storages (up to 5 000 m3) typically an insulated steel tank is used but for large storages a BTES can be considerably cheaper per unit volume of water-equivalent storage.
Seasonal Borehole Thermal Energy Storage – Guidelines for design & construction
IEA-SHC TECH SHEET 45.B.3.1
February 2015 - PDF 1.37MB - Posted: 2015-02-19
By: Bruce Sibbitt and Doug McClenahan
Borehole thermal energy storage (BTES), which is also referred to as duct storage, has been successfully used for seasonal heat storage in a number of large solar systems. Some of these systems utilize a heat pump to upgrade the stored energy to the load temperature while others use the stored heat directly without upgrading. Borehole thermal energy storages have also been used for storing cold.

BTES use the heat capacity in a large volume of native soil to store thermal energy underground. The soil itself is a very good medium for large heat storage systems since it is no-cost, already on-site, involves minimal excavation, is non-toxic and has a reasonable heat capacity. Much of the cost of a BTES is in the heat exchanger used to transfer heat to and from the soil, the drilling of boreholes in which to install the heat exchanger and in the insulation which is placed over the top of the store. For smaller storages (up to 5 000 m3) typically an insulated steel tank is used but for large storages a BTES can be considerably cheaper per unit volume of water-equivalent storage.

The purpose of this document is to provide useful guidelines for BTES design and implementation including information on how BTES performance and solar system performance are affected by a wide range of soil properties and by the shape of the BTES field, in terms of the ratio of its diameter to its depth. This information can be beneficial to the designer since in the early stages of system planning and design, soil conditions and water table depth are often unknown. In all cases, it is assumed that a BTES would not be utilized if there is a significant water movement through the bore field since the result would likely be unacceptably high heat loss.

The sensitivity results in this Tech Sheet are based on more than 1000 TRNSYS simulations of solar systems designed to meet a large fraction of the heating load at supply temperatures that are less than 40 C for most of the winter and always less than 55 C, without heat pumps. However, the results may also provide guidance for systems using heat pumps and those with higher delivery temperatures. The same systems were also simulated in 5 different Canadian climates.
Seasonal pit heat storages - Guidelines for Materials & Construction
IEA-SHC INFO SHEET 45.B.3.2
February 2015 - PDF 0.33MB - Posted: 2015-02-19
Seasonal pit heat storages has been investigated and implemented in Denmark both as pilot storages and latest also as full scale storages in Dronninglund (SUNSTORE 3) and Marstal (SUNSTORE 4). The guidelines are based on the experience from the design and implementation of the Danish pit heat storages.
Seasonal Pit Heat Storages - Guidelines for Materials & Construction
IEA-SHC TECH SHEET 45.B.3.2
February 2015 - PDF 2.47MB - Posted: 2015-02-19
By: Morten Vang Jensen
Seasonal heat storages in connection to large scale solar plants for district heating has been investigated and implemented in Denmark. For full scale systems the storages has been made as pit thermal energy storages (pit heat storages). In addition to this a borehole thermal energy storage has been implemented as a pilot plant. This fact sheet is a design guideline for pit heat storages based on experience from the design and implementation of the Danish pit heat storages.

In principle a pit heat storage is a large water reservoir for storing of thermal energy. Water is an excellent medium for heat storing as it is cheap, non-toxic and has a high heat capacity. The cost of a water storage mainly consists of the parts surrounding the water: A watertight tank and a thermal insulation. For smaller storages (up to 5 000 m3) typically an insulated steel tank is used but for larger storages a pit heat storage is considerably cheaper per m3 water (app. 1/4 of a steel tank).

Other

Fact Sheets

SHC Task 45 Fact Sheets - Overview
April 2014 - PDF 0.26MB - Posted: 2014-04-11
By: Jan Erik Nielsen, PlanEnergi
IEA-SHC Task 45 has published a number of “FACT SHEETS”. There are two types of fact sheet:

INFO SHEET: A one page introduction and summary of the technical topic
TECH SHEETS: A detailed multipage technical report/guideline dealing with the topic in detail

Highlights

Task 45 Highlights 2014
February 2015 - PDF 0.49MB - Posted: 2015-02-23
Large solar heating and cooling systems are very cost effective in some applications, for example supplying heat to an existing district heating system. The market for “Solar District Heating Systems” is developing fast in northern Europe as well as in China – and has big potential in other places. Use of seasonal storage and heat pumps makes it possible to obtain a high solar fraction (> 50%) and to interact with and level out dynamics in the electricity grid (these dynamics are increasing due to increased supply from wind turbines and PV systems). Solar district heating systems are getting rather large (a 50 MW solar collector field with a 200,000 m3 water pit storage in Denmark will begin operation in the spring of 2015).
Task 45 Highlights 2011
December 2011 - PDF 0.9MB - Posted: 2011-12-21
By: Jan Erik Nielsen
- Growing interest on “Smart District Heating”
- Price winner: Towards 100 % solar fraction in Canada
- Low solar heat production costs from large systems: 30 - 40 €/MWh

Presentations

A Booming Market for Solar District Heating
Opportunities and Challenges
October 2014 - PDF 2.91MB - Posted: 2015-01-02
By: Jan Erik Nielsen
Presentation at SHC 2014