White Paper - Adaptable System Architecture for Integrated Hydronic System.
Abstract — Complex systems, especially non-homogeneous distributed systems, are subject of uncertainties which if unmanaged can lead to inadequate performance at best or worst, to unexpected catastrophic consequences. According to Systems Architecture, every system, however big or small, is always a part of a bigger system and in turn consists of a number of smaller subsystems. This is true for both natural and technical systems. Any complex technical system, in order to be successful, has to take into account its place in the hierarchy of other systems, as well as interdependency between the components of the system on each level. This is hardly an easy task but it is becoming even more difficult under the uncertainty in changing external conditions. An important conclusion of applying the principles of Systems Architecture to such systems is that it must be adaptable. The principles of Systems Architecture are universal [1], but there is hardly a more important area where they need to be applied than the area of sustainable development in general, and energy-efficient systems for buildings and other applications in particular. This paper presents an approach to designing Adaptable System for Control Energy Network Technology on the example of the Integrated Thermal Hydronic System.
INTRODUCTION
Sustainable development has become recently the trend and a necessity. Unfortunately, “sustainability” has also added to a number of buzzwords on the market and on the political agenda: “green”, “renewable” “alternative”, “clean” etc. In ideal terms, sustainability is a system’s ability to maintain its state over time without a need for external resources or energy. In a real world we refer to it in the context of a sustainable economy, a sustainable society, a sustainable ecosystem etc. Is it a correct usage of the word? We argue it is not. We all witness that even the global economy, let alone national, is not a stable (or even predictable) system. We see profound changes in society. And there are very few who can deny that the natural environment changes with time – even if some argue about the level of impact of human activities on those changes. We need an efficient and robust but flexible approach to systems architecting, allowing adapting to constantly changing environment. For that reason instead of “sustainable” we prefer to use the terms: energy-efficient, adaptable system (including high-performance building as a system), optimal control and configuration, modular architecture, intelligent network – as applicable. While all those terms may need clarification, they can be defined much more specifically, avoiding confusion, which can lead to misleading and negative perception. There are a number of complex technical systems in different areas, from aerospace applications and satellite communication to air traffic control and national defense. Very few of them however can be characterized as truly adaptable. Here are some examples. - Startrack satellite tracking system for offshore mobile communication proved to exceed the system requirements, thanks to a simple design and optimal control algorithm. The system is well structured allowing it to be adapted to various applications and easily scaled. It was installed on a number of Caribbean cruise ships, floating platforms in North Sea and has been in successful operation for more than 15 years. Not a bad example of an adaptable system [4]. - Canadian Automated Air Traffic Control System (CAATS) promised to be an almost adaptable system. It had a well-designed distributed system architecture, which should have covered the entire Canadian and adjacent oceanic airspace and become the most advanced ATC system in the world once fully deployed. However external (economic) factors led to only partial deployment thus undermining the system’s conceptual integrity and preventing it from realizing its full potential [3]. - It was once said: “All the serious mistakes are made on the first day. Worse yet, you may have to live with them for decades”. Australian National Broadband Network (NBN) was intended to bring high-speed fiber-optic internet connection to near 100% of country’s population. In addition to bringing the nation to a forefront of today’s technology with all associated benefits, the fiber-optics superior bandwidth capacity would not be saturated for decades while transmitting and receiving equipment could be upgraded practically indefinitely at low cost, allowing the NBN to keep pace with the demand for higher data rates. Thus might be a truly adaptable system if proceeded as envisioned. However another external factor (political) intervened. The change of government led to scaling the project down. The new plan is to deploy fiber only to new developments while remaining clients would be served by bringing it only to curbside nodes. Existing copper-wire pairs will cover the so called “last mile”. Copper does not have the same capacity as fiber. Moreover, due to electrical properties of the metal, signals distort and weaken considerably with distance. This creates bottlenecks in the system. Future upgrades to a fully fiber-optic network will be much more costly [12]. Canada is currently at a similar crossroad in respect to its long-term national energy strategy. What choice will we make?
STATE OF TECHNOLOGY AFFAIRS
“More often than not, a combination of more than one technology in a system provides a better result than a stand-alone component.”
There are a number of different technologies aimed at different aspects of energy production, delivery and its efficient use. What complicates matters for consumer is that there are a number of competing products and solutions which are supposed to perform the same or overlapping functions. For example, in order to provide a building’s demand for domestic hot water and/or radiant heating / cooling one can choose from various types of geothermal systems (horizontal and vertical, open and closed loop etc.), solar thermal systems (with flat panels and vacuum solar UV collectors) and so on. In recent years air-source heat exchange systems are recognized more and more as a renewable source of energy. Less known air-to-water heat exchange systems are also getting more efficient and becoming a promising source of thermal energy. Every kind of system however has its own advantages and limitations. More often than not, a combination of more than one technology in a system provides a better result than a stand-alone component. It is important not only to choose the right components, but to find the proper combination and a balance of performance for each component and integrate them into one seamlessly functioning and efficient system.
Figure 1. Typical profiles of thermal energy production and consumption, respectively.
The aero-solar predictive algorithm, (ASPA) allows for configuration of an integrated energy system in a building or other facility, specifically an integrated thermal hydronic system. The main components of the system include: solar thermal collector, low-loss thermal storage and the thermal booster (active heat exchange). The system configuration is optimized using the ASPA predictive algorithm: the collector is optimally sized and oriented to capture maximum solar energy; the thermal booster improves the energy balance, high-efficient storage serves as a buffer smoothing the overall energy profile (Figure 1). The system automatically maintains its parameters within predetermined range and utilizes the sources of energy with most efficiency. It is done by utilizing an adaptive control algorithm with real-time feedback loop (Figure 2).
The chart on the Figure 3 below presents one of the results calculated for the sample system. One can see the strong seasonal dependency of the solar thermal energy output (red bars) which is balanced by the auxiliary components of the integrated hydronic system (IHS).
COMPETITIVE ANALYSIS
- Minimized power consumption. The electrical pumps circulating liquid in the hydronic system are the only consumers of energy in the system and use very little power. - Increased lifetime / reduced maintenance. There are no moving parts exposed to external conditions. Most of the time the pumps work at low speed, increasing system longevity. - Compact size. Configuring the system in an optimal way dramatically reduces its size. It is estimated the size of the solar thermal array can be 3 to 5 times smaller comparing to a standalone roof-mounted solar thermal system. - Autonomy. Because the system does not require drilling or excavating, which can be expensive and often not possible, it also is not dependent on specific location. This opens a number of possibilities. - Modularity. The system is designed utilizing principles of Systems Architecture. Due to inherent modularity of the system it is readily reconfigurable, components can be easily replaced or upgraded, thus allowing for evolution of the system to new technologies as they become available. - Scalability. The architecture of the system is applicable practically on any scale. The system can be also extended by connecting additional components. - Reusability. Consistent with Systems Architecture principle of re-usability the IHS design approach and adaptive control algorithm are directly transferable to an integrated energy system, utilizing for example an array of PV modules, wind turbine and a fuel-cell battery. - Network capability. The system is digitally controlled with embedded network capability allowing for remote monitoring and data processing.
POTENTIAL APPLICATIONS
Residential urban: Reduced size and cost of the integrated hydronic system (IHS) allow it to be easily installed in residential homes, a market practically abandoned by big companies. When complementing a conventional space heating and/or domestic hot water (DHW) system, the latter can be of minimal size, used mainly as a backup. Resulting energy savings such combined system accompanied by the reduction in the carbon footprint create an incentive for the residents and increase value of the property for the owner. Energy retrofit: Relatively small size and minimal to no disturbance of the existing building structure make IHS an ideal candidate for energy retrofit of the existing buildings and facilities, particularly those with high level of hot water demand, such as commercial kitchens, hotels, senior facilities, spas and swimming pools. The existing conventional DHW can be left as a backup and because being rarely used or used with a very low load, its lifespan increases dramatically. Mountain community: Absence of access to the relatively inexpensive natural gas and necessity to use more expensive propane, wider temperature ranges increasing heating demand, exacerbated by the BC Hydro rates structure, create a strong motivation for the residents of mountain communities, such as ski resorts and others, toward energy efficiency. Among the alternatives, geoexchange systems are usually more expensive than in the valley, while often not even an option due to the concerns of jeopardizing the aquifer. IHS can be an integral part of a high-performance home in such locations. Off-grid solutions: Remote rural communities, especially in Northern BC and other Provinces of Canada often do not have access to the power grid. Fully off-grid systems based on the PV array combined with high-capacity batteries are very costly. Diesel generators are often used as a power source which is not only expensive, but also environmentally damaging. With IHS the power requirements would be reduced significantly, thus allowing much smaller and therefore less expensive and “clean” off-grid solutions. Mobile applications: Being able to provide off-grid or near off-grid solution in a compact package leads to another interesting application. A number of exploration, mining, logging and other operations use portable home based camps because of the temporary or seasonal nature of their activities. With no access to a power grid and other sources, they often have to rely on diesel generator as their primary source of energy. This is also applicable to heli-skiing and many other operators. IHS delivered in a compact package provides an elegant, inexpensive and “clean” solution. This can be made even in a fully mobile version such as a tow trailer (Figure 4).
Figure 4. An example of an IHS implemented as a mobile application on a tow trailer
Intelligent network: Each system, in addition to monitoring its internal parameters, is equipped with a number of sensors - temperature, precipitation, solar irradiation etc. - information from which is used for real-time control. This, combined with network connectivity, creates one unexpected but important application. Currently accurate environmental information is available only in vicinity of weather stations (typically big cities and airports). For other areas (which is most of Canada) the information is obtained from the NASA satellites and calculated using triangulation methods producing approximate and, in some instances, inaccurate results. Being deployed in a number of different locations the systems connected in the intelligent network would share the system performance parameters, allowing for further optimization and evolution of the system. Additionally, the network can collect data to be used for accurate weather and solar mapping.
CONCLUSIONS
Combination of the optimal system configuration with adaptive control results in the integrated hydronic system (IHS) which exhibits a number of characteristics, giving it real advantages when compared to any other product on the market: it is compact, flexible, adaptable, scalable and evolvable. Connected in the intelligent network with a shared performance data repository creates an additional benefit of allowing accurate weather and solar mapping.
REFERENCES
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