Conventional Central Heating Research Articles

Performance of a novel central heating system combined with personalized heating devices

This study presents a novel central heating system that combines a conventional central heating network with personalized heating devices. The central heating network is designed to meet the basic heating demand, the indoor room temperature of which is lower than the current design values. Personalized heating devices are installed at the entrance of each indoor heating network to meet the personalized room temperature demand. The system can realize low-temperature heating when spaces are vacant and meet different room temperature demands among end users. The performance of the novel heating system is analyzed and compared with that of a conventional central heating system in terms of energy consumption and CO2 emissions under the climate conditions of Beijing and Harbin. Four types of personalized heating devices, namely, solar heaters, air source heat pumps, electrical heaters, and natural gas heaters, are discussed, and the scenarios of the four typical indoor temperature-setting modes are analyzed. When the basic room temperature is 12 °C, the maximum water supply temperatures of the central heating network is reduced from 75 °C of the traditional system to 45.8 °C (Beijing) and 52 °C (in Harbin). Under the four typical indoor temperature setting modes, the energy-saving ratio and CO2 emission reduction of the novel system are promising. In particular, if solar energy is used as the heat source of the personalized heating device in Beijing and Harbin, the primary energy consumption can be reduced by 46.3–75.7 % and 29.4–68.2 %, and CO2 emissions can be reduced by 44.4–74.5 % and 25.2–54.4 %, respectively. For all the discussed scenarios, static payback time is 1.5–8.8 y and 1.0–6.8 y in Beijing and Harbin, respectively.

A decentralized peer-to-peer control scheme for heating and cooling trading in distributed energy systems

With the increasing penetration of distributed energy resources, integrating renewable generations into energy systems is a significant trend for smart and cleaner energy systems. To this end, advanced energy management has become of great importance. Conventional control of distributed energy resources relies on a central operator, which is responsible for the energy flow from producers to consumers and regulates money transactions. As this operator or the bulk grid is a monopoly, not every user can freely connect to a distributed energy resource, and distributed energy resource s can neither compete on price and services nor decide the price of the energy they want to sell to the users. To facilitate the utilization of locally-produced energy, and balance the supply and demand, a novel decentralized competitive energy system is proposed. Through this highly automated and fully decentralized multi-energy management approach, different parties on the peer-to-peer network can conduct money transaction at the machine level without interference of the central operator. An integrated multi-layer system architecture of the competitive energy system is elaborated, including system operation mechanism, device bidding strategy, and a hardware device Energy Router. The underlying protocol for money transactions among devices is IOTA, a peer-to-peer network supporting the data and value transfer for machine economy. The proposed energy network can facilitate autonomous negotiation and execution of transactions among machines without central operator’s intervention, and prevent monopolies, as well as promote easy admission of new distributed energy resources. Furthermore, a case study of a decentralized competitive heating system is presented to demonstrate the proposed architecture, and computer simulations were conducted to verify its rationality and potential value. The simulation results indicate that the peer-to-peer heating system outperforms conventional central heating systems in terms of both user cost and system efficiency, as it encourages end users to consume locally-produced energy. The proposed decentralized solution can save 61% operation cost in heating seasons.

Earth-to-air heat exchangers cooling evaluation for different climates of Iran

Earth-pipe-air heat exchangers (EPAHEs) are viable alternatives or supplements to conventional central heating or cooling systems. In present study, to reduce the cooling load of a sample residential building; usage and potential energy conservation of a four-pipe EPAHE were studied for different climates of Iran. The evaluation of the EPAHE was based on a three-dimensional transient computational model and validated by experimental data of another research. For this purpose four cities of Iran, by different climates (Temperate, Steppe, Desert, and Snow) were selected according to climate classification map of Wladimir Köppen, and the inlet/outlet temperature of working fluid (air) for each pipe, the monthly average energy conservation, and the maximum cooling load of the building with and without the EPAHE for these cities were compared in July.As a result, the average energy conservation by the EPAHE is significantly differentin selected cities with different climates. The energy conservation shows better when the city soil, is silt in comparison with loam and clay. Also in some cases, using of EPAHE shows a negative effect on the air-conditioning of buildings. The model was developed by the FLUENT simulation program.

Economic Feasibility Study of Modern and Conventional Central Heating Systems for Villa Located in Duhok City, Iraq

This research includes the evaluation of economic feasibilities based on the Iraqi’s market cost by using three different types of central heating systems in a residential villa located in Duhok city / Iraq. It also compares between modern and conventional central heating systems. A life cycle cost analysis based on detailed heating and operation load profiles considered in this work. Initial, running and maintenance costs for three central heating systems examined for fifteen years as a working period. The used systems in this study were; modern central heating system (heat pump water heater system) and conventional central heating system (fuel oil hot water boiler system and electric hot water boiler system). Transfer function method with hourly analysis program platform (HAP4.9) used for estimation the heating loads within each zone of the project. The proposed technique of modern central heating system found to be more efficient for thermal and economic efficiencies and it uses an environmentally friendly refrigerant such as (R410A). It also works efficiently in severe cold climate with low temperature of (-20°C) in winter season. The results shows that the heat pump water heater central heating system is most efficient system, this system has provided an energy saving range up to 57.5% compared with electric hot water boiler system and 70.6% compared with fuel oil hot water boiler system.

Application of concept of heat adaptor: Determining an ideal central heating system using industrial waste heat

In northern China, urban heating energy consumption accounts for about 40% of the total building energy consumption and emits a lot of pollutants to atmosphere environment, while tremendous low grade industrial waste heat is discharged into the environment. Utilizing these industrial waste heat for central heating in winter is of great importance in energy saving and atmosphere environment protection. Hence, it raised more concerns during recent years. However, in traditional systems, such waste heat is used to produce relatively low temperature supply water through heat exchangers. It leads to large mass flow rate in the primary network, which results in huge pumping energy consumption after long distance delivery, since the heating users are often far away from the industrial waste heat sources. In this paper, applying the concept of heat adaptor put forward in our previous paper, an ideal central heating system using such industrial waste heat is determined. It is composed of two heat adaptors at heat source and substations respectively. The optimal return water temperature in the primary network of the ideal central heating system is derived to be the ambient air temperature. Compared with a conventional central heating system including heat exchanger system or absorption heat exchanger system, the return water temperature, mass flow rate and delivery pumping energy consumption of an ideal central heating system can be decreased greatly. In the illustrative example, the delivery pumping energy consumption is reduced by 82%, by using the proposed ideal central heating system. It is hoped that the method developed in the present paper is helpful for optimization design of practical central heating systems using industrial waste heat.

Thermodynamic analysis and life cycle assessment of the heating strategies in historical buildings: a case study

This paper presents the thermodynamic analysis and life cycle assessment (LCA) of the heating strategies in historical buildings. We evaluated two main systems used in historical buildings to provide heat: a central heating system, which is based on a method of heating the whole air volume within the building, and a localised heating system, which is based on a method of supplying the desired amount of heat to the individual occupants. After evaluating both systems in a historic mosque, we found that using a modern localised heating system like the carbon film heating, a comfortable temperature can be maintained while saving 22.4 MWh of electricity annually, compared with a conventional central heating system. Moreover, the carbon film heating system can reduce stress on the environment by 60% when compared with the conventional heat pump system.

Flexibility of a combined heat and power system with thermal energy storage for district heating

The trend towards an increased importance of distributed (renewable) energy resources characterized by intermittent operation redefines the energy landscape. The stochastic nature of the energy systems on the supply side requires increased flexibility at the demand side. We present a model that determines the theoretical maximum of flexibility of a combined heat and power system coupled to a thermal energy storage solution that can be either centralized or decentralized. Conventional central heating, to meet the heat demand at peak moments, is also available. The implications of both storage concepts are evaluated in a reference district. The amount of flexibility created in the district heating system is determined by the approach of the system through delayed or forced operation mode. It is found that the distinction between the implementation of the thermal energy storage as a central unit or as a collection of local units, has a dramatic effect on the amount of available flexibility.

06/02484 Experimental investigation of a low energy consumption air conditioning system based on conventional central heating installation: Bakos, G. C. et al. Energy and Buildings, 2006, 38, (1), 45-52.

06/02484 Experimental investigation of a low energy consumption air conditioning system based on conventional central heating installation: Bakos, G. C. et al. Energy and Buildings, 2006, 38, (1), 45-52.

Experimental investigation of a low energy consumption air conditioning system based on conventional central heating installation

This paper deals with the development of a low cost and low energy consumption air conditioning system based on the conventional central heating installations. It is aimed to convert, with minimal cost and work intervention in the interior of the buildings, the classic central heating systems into a new type system which can cool during summer and heat during winter period. In general, the above mentioned heating–cooling system constitutes an integrated new technology in building air conditioning, with good prospects in replacing eventually the conventional air conditioning systems. The experimental installation is described in detail and the experimental results are presented and analysed. The achieved energy saving is also calculated. The advantages and disadvantages of the proposed system are discussed and useful conclusions are drawn.

ESTIMATION OF THE WATER-MASS-FLOW THROUGH A CENTRAL HEATING BOILER

Conventional central heating systems in German buildings are hot-water heating systems. These systems consist of a boiler and radiators or heating coils in the floor. A heating characteristic maps the current outdoor temperature to the set-point of the boiler outlet-temperature. Conventional PI-controllers with fixed parameters adjust the boiler outlet-temperature to the set-point. Since the process of heating water in the boiler is nonlinearly dependent on the water-mass-flow, knowledge of the flow-rate could improve the quality of control. This paper presents two different observer-based schemes for the estimation of the water flow rate through a central heating boiler. One is a disturbance observer and the other is a parameter observer.

Energy and economic comparisons of a heat pump/heat store with conventional heating systems in the British climate

The thermodynamic and economic performance of a heat pump combined with a water heat store has been examined. The thermal store contains electrical resistance heaters which can boost the water temperature to 95°C. By utilising the off-peak tariffs for electricity it has been shown that the heat pump/heat store can compete economically with conventional central heating systems, based on an oil-fired boiler, a coal-fired boiler, or night storage heaters. To stand comparison with gas central heating, however, the cost of gas would have to increase by 6%, the capital cost of the heat pump/heat store be reduced by 20%, or the seasonal performance of the heat pump/heat store be improved by 17%.

Energy and monetary benefits of portable heaters

A methodology is outlined that has been used to study the sensitivity of the performance of portable electric and kerosene space heaters to several parameters, including: the price of fuel for the conventional central heating system, the price of portable heater fuel, the thermal integrity of the structure, the size of the room that the portable heater is used to heat, the setback temperature for the central heating system, the duration of use, rates of air exchange with other spaces, and geographic location. Results are used to identify the conditions for which portable heaters are most beneficial and to which parameters the savings are most sensitive. The results show that savings are most sensitive to the thermal integrity of the structure, the price of fuel for the conventional heater, the thermostat setting during setback, and the duration of use of the portable heater. Payback periods for portable heaters are found to range from several months to more than six years.

Electrical automatic controls for space heating

Postwar developments in building have increased the importance of automatic controls for heating and air-conditioning installations because of the demand for comfortable environmental conditions and the large potential saving of fuel obtainable with appropriate controls. The reasons why the actual performance of heating controls is often unsatisfactory are considered.The characteristics of buildings and heating systems affecting the design and selection of automatic controls are discussed, and the principal elements of control systems are described, particular attention being devoted to improvements considered necessary to overcome difficulties in application.The application of these elements to typical systems of electrical heating, conventional central heating and air conditioning is then considered, and the paper concludes by discussing the problems of installation and maintenance and demonstrates how these can be alleviated by suitable design procedures.

Electrical automatic controls for space heating

Postwar developments in building have increased the importance of automatic controls for heating and air-conditioning installations because of the demand for comfortable environmental conditions and the large potential saving of fuel obtainable with appropriate controls. The reasons why the actual performance of heating controls is often unsatisfactory are considered.The characteristics of buildings and heating systems affecting the design and selection of automatic controls are discussed, and the principal elements of control systems are described, particular attention being devoted to improvements considered necessary to overcome difficulties in application.The application of these elements to typical systems of electrical heating, conventional central heating and air conditioning is then considered, and the paper concludes by discussing the problems of installation and maintenance and demonstrates how these can be alleviated by suitable design procedures.