Eliminating oscillations in TRV controlled hydronic radiators

Abstract — Thermostatic Radiator Valves (TRV) have proved their significant contribution in energy savings for several years. However, at low heat demands, an unstable oscillatory behavior is usually observed and well known for these devices. This instability is due to the nonlinear dynamics of the radiator itself which result in a large time constant and high gain for radiator at low flows. A remedy to this problem is to make the controller of TRVs adaptable with the operating point instead of widely used fixed PI controllers. To this end, we have derived a linear parameter varying model of radiator, formulated based on the operating flow rate, room temperature and the radiator specifications. In order to derive such formulation, the partial differential equation of the radiator heat transfer dynamics is solved analytically. Using the model, a gain schedule controller among various possible control strategies is designed for the TRV. It is shown via simulations that the designed controller based on the proposed LPV model performs excellent and stable in the whole operating conditions. I

Heating controls: International evidence base and policy experiences

This report presents a synthesis in the form of narrative summaries of the international evidence base and policy experiences on heating controls in the domestic sector. The research builds on the former Department of Energy and Climate Change (DECC) commissioned (systematic) scoping review of the UK evidence on heating controls published in 2016 (Lomas et al., 2016), and the Rapid Evidence Assessment of smarter heating controls published in 2014 (Munton et al., 2014). The report consists of two parts. Part 1 involves a (systematic) scoping review of the international evidence base on the energy savings, cost-effectiveness and usability of heating controls in the domestic sector. Part 2 contains the findings from an analysis of the policy experiences of other countries

Component based performance simulation of HVAC systems

The design process of HVAC (Heating, Ventilation and Air Conditioning) systems is based upon selecting suitable components and matching their performance at an arbitrary design point, usually determined by an analysis of the peak environmental loads on a building. The part load operation of systems and plant is rarely investigated due to the complexity of the analysis and the pressure of limited design time. System simulation techniques have been developed to analyse the performance of specific commonly used systems: however these 'fixed menu, simulations do not permit appraisal of hybrid and innovative design proposals. The thesis describes research into the development of a component based simulation technique in which any system may be represented by a network of components and their interconnecting variables. The generalised network formulation described is based upon the engineer's schematic diagram and gives the designer the same flexibility in simulation as is available in design. The formulation of suitable component algorithms using readily available performance data is discussed, the models developed being of a 'lumped parameter' steady state form. The system component equations are solved simultaneously for a particular operating point using a gradient based non-linear optimisation algorithm. The application of several optimisation algorithms to the solution of RVAC systems is described and the limitations of these methods are discussed. Conclusions are drawn and recommendations are made for the required attributes of an optimisation algorithm to suit the particular characteristics of HVAC systems. The structure of the simulation program developed is given and the application of the component based simulation procedure to several systems is described. The potential for the use of the simulation technique as a design tool is discussed and recommendations for further work are made

Enhancement of panel radiator based hydronic central heating system using flow pulsation

Enhancing the heat output of the hydronic central heating system in buildings can play a major role in reducing energy consumption and CO2 emission. The main aim of this PhD research is to investigate the effect of pulsed flow input on the energy consumption of panel radiators in hydronic central heating systems and the user indoor comfort defined by ASHRAE standard 55 and EN ISO 7730. The research covers thermal performance of panel radiator and the indoor comfort. The work was performed using dynamic control modelling, CFD and experimental testing to prove the concept. Results from the mathematical and CFD modelling of the hydronic radiator with pulsed flow using various frequencies and amplitudes showed that 20% to 27% of energy saving can be achieved compared to the constant flow while maintaining the same radiator target surface temperature of 50oC as recommended by the BS EN442. The indoor comfort results were also achieved as recommended by international standards including CO2 concentration at 1000PPM±50PPM, relative humidity at 50±9%, comfort temperature at 20±1.6oC, air velocity of below 0.15m/s and draught risk parameters of less than 15%. The numerical results agreed well with experimental results with maximum deviation of radiator temperature output of ±4.1%, indoor temperature ±2.83% and energy saving of ±1.7%. The energy saved due to the pulsed flow is attributed to the enhancement of the radiator heat transfer performance that leads to higher heat output at lower average mass flow rate of the hot water

An Examination of the US Residential Heating Market

This paper outlines the US residential space heating market and highlights thirteen disruptive companies whose products decarbonize some link in the space heating supply chain. The goal of the paper is to provide Energy Impact Partners (EIP) with a strong understanding of market trends, regional switching costs, customer behaviors, and policy incentives. Additionally, we present an investment landscape of disruptive companies from which EIP may choose to pursue specific investment objectives. The US residential space heating market may be thought of as a mix of space heating fuel sources, such as natural gas and electricity, and a mix of space heating technologies, such as Furnaces and Heat Pumps. Four major trends stick out. First, Furnaces dominate the technology landscape as the most popular heating technology. Second, natural gas and electricity are the two main fuel types used for space heating, with 51% of households using natural gas and 37% of households using electricity. Third, the mixes of fuel and equipment have changed since 2001 largely due to higher population growth in southern regions where electricity and Heat Pumps provide space heating for most homes. Fourth, according to utility executives interviewed the mix of fuel and technology will not change drastically over the next ten years. Payback periods calculated are often long, greater than 10 years, making the switch to less carbon intensive fuel sources or less energy intensive technologies less appealing to the average homeowner. Furthermore, customer behavior hinders the switch to decarbonizing technologies because most individuals do not view space heating equipment as aspirational purchases and will only replace equipment upon failure – which often happens during the winter – forcing them to seek out the quickest fix rather than shop around for an alternative option, even if that option can save money through lower operating costs. Several federal and state incentives exist to motivate homeowners to decarbonize their space heating system. More details are provided in Chapter 7. Ultimately, the paper concludes with four insights for EIP with regards to investing in space heating startups. These insights revolve around the projected energy and technology mix, where innovation occurs in the space heating supply chain, customer behavior in purchasing decisions, and the importance of government policy for a startup’s success.Master of ScienceSchool for Environment and SustainabilityUniversity of Michiganhttps://deepblue.lib.umich.edu/bitstream/2027.42/146738/1/An Examination of the US Residential Heating Market_338.pd

Heating controls scoping review project

This report summarises the findings of an evidence review of the energy savings, cost-effectiveness and usability of different types of heating controls

Application of a new dynamic heating system model using a range of common control strategies

This research investigates the overall heating energy consumptions using various control strategies, secondary heat emitters, and primary plant for a building. Previous research has successfully demonstrated that a dynamic distributed heat emitter model embedded within a simplified third-order lumped parameter building model is capable of achieving improved results when compared to other commercially available modelling tools. With the enhanced ability to capture transient effects of emitter thermal capacity, this research studies the influence of control strategies and primary plant configurations on the rate of energy consumption of a heating system. Four alternative control strategies are investigated: zone feedback; weather-compensated; a combination of both of these methods; and thermostatic control. The plant alternative configurations consist of conventional boilers, biomass boilers, and heat pumps supporting radiator heating and underfloor heating. The performance of the model is tested on a primary school building and can be applied to any residential or commercial building with a heating system. Results show that the new methods reported offer greater detail and rigor in the conduct of building energy modelling