The impact of control strategies on space heating system efficiency in low-energy buildings

2019 ◽  
Vol 40 (6) ◽  
pp. 714-731
Author(s):  
Christian Brembilla ◽  
Ronny Renman ◽  
Mohsen Soleimani-Mohseni ◽  
Ronny Östin ◽  
Thomas Olofsson
Keyword(s):  
Mass Flow Rate ◽  
Flow Rate ◽  
Control Strategies ◽  
Heating System ◽  
Energy Performance ◽  
Low Energy ◽  
Space Heating ◽  
Building Models ◽  
Non Linear ◽  
Efficiency Factors

In this study efficiency factors measure the thermal energy performance for space heating. This study deals with the influence of control strategies on the efficiency factors of space heating and its distribution system. An adaptive control is developed and applied to two types of heating curves (linear and non-linear) for a low-energy building equipped with renewable energy sources. The building is modelled with a hybrid approach (law-driven + data-driven model). The model of the floor heating is calibrated and validated by assessing the uncertainty bands for flow temperatures and mass flow rate. Benefits and drawbacks of linear and non-linear heating curves are highlighted to illustrate their impact on space heating thermodynamic behaviour and on the efficiency factors of the space heating system. Practical application: The study reveals that applying commercial building energy simulation software is worthwhile to determine reliable energy performance predictions. Massless building models are not capable of simulating the thermodynamic response of a building subjected to different control strategies. In particular, the application of different heating curves (linear and non-linear) to massless building models leaves the amount of mass flow rate delivered to the space heating unchanged when the building is subjected to sharp variations of the outdoor temperature.

scholarly journals Nonlinear Model Establishment and Experimental Verification of a Pneumatic Rotary Actuator Position Servo System

Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 1096 ◽  
Author(s):  
Yeming Zhang ◽  
Ke Li ◽  
Geng Wang ◽  
Jingcheng Liu ◽  
Maolin Cai
Keyword(s):  
Heat Transfer ◽  
Linear Model ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Experimental Verification ◽  
Servo System ◽  
Rotary Actuator ◽  
Non Linear ◽  
Position Servo

In order to accurately reflect the characteristics and motion states of a pneumatic rotary actuator position servo system, an accurate non-linear model of the valve-controlled actuator system is proposed, and its parameter identification and experimental verification are carried out. Firstly, in the modeling of this system, the mass flow rate of the gas flowing through each port of the proportional directional control valve is derived by taking into account the clearance between the valve spool and the sleeve, the heat transfer formula is used to the derivation of the energy equation, and the Stribeck model is applied to the friction model of the pneumatic rotary actuator. Then, the flow coefficient, the heat transfer coefficient and the friction parameters are identified by the model and pneumatic test circuits. After the verification experiment of the mass flow rate equations, the charging and discharging experiment reveals that the model can clearly show the effect of clearances on gas pressure changes and describe the effect of heat transfer on gas temperature changes. Finally, the results of model verification indicate that the simulation curves of rotation angle and two-chamber pressures are consistent with their experimental values, and the non-linear model shows high accuracy.

scholarly journals Practical support for evaluating efficiency factors of a space heating system in cold climates

2017 ◽  
Vol 10 (5) ◽  
pp. 1253-1267 ◽  
Author(s):  
Christian Brembilla ◽  
Mika Vuolle ◽  
Ronny Östin ◽  
Thoms Olofsson
Keyword(s):  
Heating System ◽  
Space Heating ◽  
Cold Climates ◽  
Practical Support ◽  
Efficiency Factors

Energy Performance of School Buildings by Construction Periods in Federation of Bosnia and Herzegovina

Buildings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 42
Author(s):  
Dragan Katić ◽  
Hrvoje Krstić ◽  
Saša Marenjak
Keyword(s):  
Bosnia And Herzegovina ◽  
Heating System ◽  
Energy Performance ◽  
Climatic Conditions ◽  
Building Envelope ◽  
Space Heating ◽  
School Buildings ◽  
Energy Costs ◽  
Improve Energy Efficiency ◽  
Construction Periods

This paper is part of broader research aimed at determining the relationship between energy performance and energy costs as a part of the operational and life cycle costs in school buildings in the Federation of Bosnia and Herzegovina (FBiH), as exceptionally important social and public buildings. The research was conducted by statistical analysis of data collected from documents of detailed energy audits (DEA) for 185 school buildings in FBiH in relation to construction periods. The paper analyzes the characteristics of buildings such as construction period, building envelope characteristics, climatic conditions, efficiency of installed space heating system, number of users and heating mode. The aim of this research was to determine the energy performance for the existing state and to compare them with the allowable values in accordance with the applicable legal regulations. There is a performance gap between predicted (calculated) and measured (actual) delivered energy for space heating. This research shows poor energy performance and provides a basis for developing strategies and plans to improve energy efficiency. The results of the energy performance of school buildings in the FBiH are the first step towards the development of a model for predicting energy costs.

scholarly journals A method for estimating scheduled and manual override heating behaviour and settings from measurements in low energy UK homes

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Adorkor Bruce-Konuah ◽  
Rory V. Jones ◽  
Alba Fuertes
Keyword(s):  
Air Temperature ◽  
Questionnaire Survey ◽  
Heating System ◽  
Low Energy ◽  
Space Heating ◽  
Living Room ◽  
Content Type ◽  
Energy Demands ◽  
Alternative Method ◽  
Heating Duration

PurposeThe purpose of this paper is to present a methodology for estimating scheduled and manual override heating events and heating settings from indoor air temperature and gas use measurements in UK homes.Design/methodology/approachLiving room air temperature and gas use data were measured in ten UK homes built to low energy standards. The temperature measurements are used to establish whether the central heating system is turned on or off and to estimate the heating setpoint used. The estimated heating periods are verified using the homes' average daily gas consumption profiles.FindingsUsing this method, the average number of heating periods per day was 2.2 (SD = 0.8) on weekdays and 2.7 (SD = 0.5) on weekends. The weekday mean heating duration was 8.8 h and for weekends, it was 9.8 h. Manual overrides of the settings occurred in all the dwellings and added an average of 2.4 h and 1.5 h to the heating duration on weekdays and weekends respectively. The mean estimated setpoint temperatures were 21.2 and 21.4°C on weekdays and weekends respectively.Research limitations/implicationsManual overrides of heating behaviours have only previously been assessed by questionnaire survey. This paper demonstrates an alternative method to identifying these manual override events and responds to a key gap in the current body of research that little is currently reported on the frequency and duration of manual heating overrides in UK homes.Practical implicationsThe results could be used to better inform the assumptions of space heating behaviour used in energy models in order to more accurately predict the space heating energy demands of dwellings.Originality/valueManual overrides of heating behaviours have only previously been assessed by questionnaire survey. This paper demonstrates an alternative method to identifying these manual override events and responds to a key gap in the current body of research that little is currently reported on the frequency and duration of manual heating overrides in UK homes.

scholarly journals Determination of cop maximum of cold water loop of heat pump heating system by means of numerical-graphical optimization procedure

2020 ◽  
pp. 104-104
Author(s):  
Zoltan Pek ◽  
Arpad Nyers ◽  
Jozsef Nyers
Keyword(s):  
Mathematical Model ◽  
Mass Flow Rate ◽  
Heat Pump ◽  
Mass Flow ◽  
Flow Rate ◽  
Water Mass ◽  
Cold Water ◽  
Energy Optimization ◽  
Heating System ◽  
Water Mass Flow Rate

The paper presents the energy optimization of the cold water loop of the heat pump heating system using analytical-numerical procedure. The aim of the study is obtain the maximum COP of the heating system by optimum of the wall water mass flow rate and well pump power. The objective function is the heating system's coefficient of performance (COP). All components of the heating system: evaporator, condenser, compressor, circulation pump and well pump are described by steady-state, lumped mathematical model. The model?s equations are coupled, non-linear, multivariable and algebraic the solution is feasible using an iterative numerical method. Matlab?s program with Gauss elimination and Newton linearization method is applied for solving the model. The obtained numerical data are presented in 3D graphics. The optimum value of the cold-well water mass flow rate is obtained from the graphics or by using a selection algorithm. The results of the study are the adequate mathematical model for energy optimization of the heating system, the numerical algorithm for solving the model and the ultimate goal to obtain the optimum of the power of well pump and compressor.

A Brief Model to Evaluate the Behaviour of R134a/R1234yf Mixtures on a Reciprocating Compressor

2015 ◽  
Author(s):  
J. M. Barroso-Maldonado ◽  
J. M. Belman-Flores ◽  
C. Rubio-Maya
Keyword(s):  
Energy Consumption ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Energy Savings ◽  
Energy Performance ◽  
Error Band ◽  
Discharge Temperature ◽  
Mass Fractions ◽  
Discharge Pressure

Transitioning from R134a refrigerant to a low global warming potential (GWP) refrigerant is a current issue of global importance. Although any refrigerant still has set; there are a few options to replace it such as the R1234yf. In this paper is presented a semi-empirical model to assess the energy performance of mixtures with R134a and its possible substitute R1234yf. The inputs variables to the computational model are: suction conditions (pressure and temperature), discharge pressure and rotation speed. With these variables the model must compute the following parameters: mass flow rate, discharge temperature and energy consumption. The model is validated with data obtained from an experimental facility; calculations are obtained within a relative error band of ±10% for mass flow rate and energy consumption, and an error of ±1 K for discharge temperature. Finally, the model is carried out to an energy simulation in order to predict the behavior of different mass fractions of R1234yf. Energy savings are found when R1234yf mass fraction is reduced from 1 to 0.9. Knowing that the mixture with y=0.9 may be used as its GWP is 150.

scholarly journals Mass flow rate optimization in solar heating systems based on a flat-plate solar collector: A case study

2021 ◽  
Vol 12 (3) ◽  
pp. 061-071
Author(s):  
Samer Yassin Alsadi ◽  
Tareq Foqha
Keyword(s):  
Flat Plate ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Solar Collector ◽  
Optimization Problems ◽  
Heating System ◽  
Solar Heating ◽  
Outlet Temperature ◽  
Solar Systems

Little works considered the optimization of working fluids in solar systems. Engineers, designers and scientists are interested with the optimization problems, furthermore it is very important specially, for solar systems to improve the energetic behavior and increase their efficiencies as a conversion system of solar irradiance to a useful thermal power. According to the available literature, the criteria of optimization mainly relates to energetic and economic analysis (one of them or both). The analysis was based upon the maximum useful energy obtained from solar collector. Accordingly, the optimum mass flow rate was found aspires to infinity. The second analysis is based upon minimum cost of the unit of useful energy [$/W]. The optimum mass flow rate of solar air-heating flat-plate collector for the considered domestic solar heating system has been found 29 kg/h per square meters of solar collectors. This paper deals with a third criteria that is, the amount of the additional energy required to achieve the required task from the solar system by means of auxiliary heating system. In where both the outlet temperature and mass flow rate play crucial role in the heat exchange between the fluid in the collector loop and the fluid in the load loop.

scholarly journals The Impact of Width of the Air Gap Channel on the Mass Flow Rate, Rayleigh Number, and Efficiency of Passive Solar Heating System

2018 ◽  
Vol 25 (3) ◽  
pp. 47-52 ◽  
Author(s):  
Ehsan F. Abbas ◽  
Shayma A. Azat
Keyword(s):  
Rayleigh Number ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Winter Season ◽  
Heating System ◽  
Air Gap ◽  
Trombe Wall ◽  
Passive Solar ◽  
The Impact

The mass flow rate and Rayleigh number has been investigated experimentally on the passive solar using Trombe wall consist of (industrial wax) used as phase change material (PCM). A test rig of a cubicle was made of PVC sandwich panel except the south wall, Trombe wall; covered with a clear glass of 6 mm thickness. The six experiments were carried out during the winter season in Kirkuk city with six different widths of the air gap channel (10, 15, 20, 25, 30, and 35) cm. The experimental resultts show that the mass flow rate proportional directly to a width of the channel and inversely with Rayleigh number. Moreover, the highest efficiency was obtained at a depth of 30 cm, where it was about 2.45 times the efficiency of 10 cm.

scholarly journals A Study on Developing an Automatic Controller with an Inverter Collector Pump for Solar-Assisted Heating System

Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2128
Author(s):  
Le Minh Nhut ◽  
Youn Cheol Park
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Variable Mass ◽  
Heating System ◽  
Input Module ◽  
Embedded Controller ◽  
Useful Heat Gain ◽  
Variable Mass Flow ◽  
The Stability

In this study, based on the optimal equation m = 0.05 Δ T A c (kg/min) of the variable mass flow rate in the collector loop, an automatic controller with an inverter collector pump for the collector loop of the solar-assisted heating system is designed for these experiments and to then be used for real industry. The pump for the collector loop is an inverter type that is controlled by an embedded controller with Windows, based on C# language, and the change of speed depends on the variation of the mass flow rate through the collector loop. The input of the automatic controller with an inverter collector pump is given by a thermocouple input module that is connected to the embedded controller with the RS-485 communication protocol. In this work, the experiments were carried out on three different days, namely a clear day, an intermittently cloudy day and an overcast day, to evaluate the stability and the precision of the automatic controller, as well as the contribution of the useful heat gain from the collector for the solar-assisted heating system. Simulation and experimental results are also validated and analyzed.

scholarly journals To Combine or Not To Combine An In-Depth Review of Standard and Combined Hydronic Systems and Their Various Pitfalls

1993 ◽  
Vol 10 (2) ◽  
Author(s):  
Edward W. Saltzberg
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
Heat Exchangers ◽  
Water Flow Rate ◽  
Heating System ◽  
Hot Water ◽  
Space Heating ◽  
System Pressure ◽  
Hot Water Supply ◽  
Heating Boiler

A hydronic heating system is simply a piping arrangement conveying hot water to heat exchangers in order to provide space heating. A conventional hydronic heating system usually delivers hot supply water at 180 to 200 Fahrenheit temperature and has a dedicated space heating boiler. The hot water return temperature is usually about 140 Fahrenheit, meaning a 40 to 60 temperature difference between supply and return. The conventional hydronic heating system has a relatively constant circulated water flow rate and the temperature of the delivered hot water supply can be reset from outside air temperature. The water flow balancing of a conventional hydronic heating system is somewhat straightforward, although quite critical. The pipe sizing is determined on the basis of gallons per minute flow rate, the selected system pressure drop, and the maximum prudent velocity for the specific piping material. The circulating pump is selected on the basis of the required gallons per minute

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