scholarly journals Determination of Heat Losses from the Pipeline in SDHW System during the Continuous Change of the Supply Temperature

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 90
Author(s):  
Miroslaw Zukowski
Keyword(s):  
Heat Loss ◽  
Classical Method ◽  
Heating System ◽  
Heat Losses ◽  
Hot Water ◽  
Continuous Change ◽  
Energy Balancing ◽  
Practical Result ◽  
The Impact

In this article, the research object is the solar domestic hot water (SDHW) heating system that has been in operation since 2015 and is located on the campus of the Bialystok University of Technology (Poland). The thermal performance of solar collectors are thoroughly investigated so far. Therefore, special attention was paid to the issue of the heat loss from pipes. The measurements showed that the heat transfer in circulation pipes is quite complex due to continuous fluctuations in water temperature at the supply of this loop. As it turned out, the application of the classical method of energy balancing and the readings from heat meters gave inaccurate results in this case. The main aim of this study was to develop a different approach to solving the problem of determination of heat losses. The method presented in this article is based on computational fluid dynamics (CFD) and measurement results as the input data. The practical result of this study was the development of two relationships for calculating the heat loss from pipes. A separate issue, that is discussed in this paper, concerns the impact of the time intervals used in numerical simulations on the accuracy of calculation results.

scholarly journals Overview of Solutions for the Low-Temperature Operation of Domestic Hot-Water Systems with a Circulation Loop

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3350
Author(s):  
Theofanis Benakopoulos ◽  
William Vergo ◽  
Michele Tunzi ◽  
Robbe Salenbien ◽  
Svend Svendsen
Keyword(s):  
Low Temperature ◽  
Heat Loss ◽  
District Heating ◽  
Heating System ◽  
Hot Water ◽  
Heating Power ◽  
Circulation Loop ◽  
Space Heating ◽  
District Heating System ◽  
Domestic Hot Water

The operation of typical domestic hot water (DHW) systems with a storage tank and circulation loop, according to the regulations for hygiene and comfort, results in a significant heat demand at high operating temperatures that leads to high return temperatures to the district heating system. This article presents the potential for the low-temperature operation of new DHW solutions based on energy balance calculations and some tests in real buildings. The main results are three recommended solutions depending on combinations of the following three criteria: district heating supply temperature, relative circulation heat loss due to the use of hot water, and the existence of a low-temperature space heating system. The first solution, based on a heating power limitation in DHW tanks, with a safety functionality, may secure the required DHW temperature at all times, resulting in the limited heating power of the tank, extended reheating periods, and a DH return temperature of below 30 °C. The second solution, based on the redirection of the return flow from the DHW system to the low-temperature space heating system, can cool the return temperature to the level of the space heating system return temperature below 35 °C. The third solution, based on the use of a micro-booster heat pump system, can deliver circulation heat loss and result in a low return temperature below 35 °C. These solutions can help in the transition to low-temperature district heating.

Evacuated Tube Heat Pipe Solar Collectors Applied to Recirculation Loop in a Federal Building: SSA Philadelphia

Solar Energy ◽  
2004 ◽  
Author(s):  
Andy Walker ◽  
Fariborz Mahjouri ◽  
Robert Stiteler
Keyword(s):  
Solar Energy ◽  
Heat Pipe ◽  
Heat Loss ◽  
Heating System ◽  
Hot Water ◽  
Solar Array ◽  
Solar Collectors ◽  
Water Heating ◽  
Evacuated Tube ◽  
Recirculation Loop

This paper describes design, simulation, construction and measured initial performance of a solar water heating system (360 Evacuated Heat-Pipe Collector tubes, 54 m2 gross area, 36 m2 net absorber area) installed at the top of the hot water recirculation loop in the Social Security Mid-Atlantic Center in Philadelphia. Water returning to the hot water storage tank is heated by the solar array when solar energy is available. This new approach, as opposed to the more conventional approach of preheating incoming water, is made possible by the thermal diode effect of heat pipes and low heat loss from evacuated tube solar collectors. The simplicity of this approach and its low installation costs makes the deployment of solar energy in existing commercial buildings more attractive, especially where the roof is far removed from the water heating system, which is often in the basement. Initial observed performance of the system is reported. Hourly simulation estimates annual energy delivery of 111 GJ/year of solar heat and that the annual efficiency (based on the 54 m2 gross area) of the solar collectors is 41%, and that of the entire system including parasitic pump power, heat loss due to freeze protection, and heat loss from connecting piping is 34%. Annual average collector efficiency based on a net aperture area of 36 m2 is 61.5% according to the hourly simulation.

scholarly journals INSTALLATION FOR DETERMINATION OF HEAT RELEASE OF HEATING RADIATORS

2021 ◽  
Vol 4 (164) ◽  
pp. 77-81
Author(s):  
Yu. Ivashina ◽  
V. Zavodyannyi
Keyword(s):  
Heat Transfer ◽  
Heat Loss ◽  
Electrical Power ◽  
Electric Heating ◽  
Middle Part ◽  
Heat Losses ◽  
The Body ◽  
Heat Output ◽  
Stationary Mode

To calculate the share of thermal energy consumed by this apartment in an apartment building, it is necessary to determine the heat transfer of all heating radiators in the house. But the heat transfer given in the passport of the heating device corresponds to the temperature pressure equal to 70K. Often the owners install non-standard devices, so the problem of determining the heat transfer of heating radiators in real conditions is relevant. Thermometric method, which is called electric, is widely used for laboratory determination of heat transfer of heating devices. Water by means of the pump circulates through an electric copper and the investigated radiator. The heat output of the latter is defined as the difference between the supplied electrical power (boiler power plus pump) and heat loss. The purpose of the work is to develop and study the operation of the installation for determining the heat transfer of heating radiators, which had a simpler design and could ensure proper measurement accuracy. We have proposed a scheme and design of the installation for determining the heat transfer of electric heating radiators, which differs in that it does not include a circulating pump. Water in the system circulates under the action of gravity due to changes in the density of the coolant during heating and cooling. This greatly simplifies the circuit by eliminating not only the pump but also the valve and the air outlet valve. The heater chamber is made of a steel pipe with a diameter of 88 mm. A steel cover is attached to the lower flange, through which a 1-1.5 kW heater is introduced into the chamber. Two 1/2 ″ sections of pipe are welded to the body of the heater chamber, through which the radiator is connected by means of rubber couplings. The cylindrical surface of the chamber on top of the layer of internal insulation is covered with a shielding heater, the temperature of which is maintained equal to the surface temperature of the heater chamber in the middle part. A layer of external thermal insulation is installed on top of the shielding heater. To determine heat loss, the radiator is disconnected from the heater chamber, plugs are installed and insulated. In stationary mode, the dependence of the heater power on the temperature of the heater chamber is measured, which determines the power of heat losses. The simplification of the installation has led not only to its reduction in price, but also to an increase in accuracy due to the reduction of heat losses and the simplicity of their definition.

scholarly journals Calculation Of Heat Loss Through The Pipes Of The Interior Central Heating System

2015 ◽  
Vol 5 (2) ◽  
pp. 29-36 ◽  
Author(s):  
I. Giurca
Keyword(s):  
Heat Loss ◽  
Heating System ◽  
Building Energy ◽  
Local Heat ◽  
Heat Losses ◽  
Energy Audit ◽  
Heating Systems ◽  
Central Heating ◽  
Calculation Methodology

Abstract The article presents aspects related to the calculation of heat loss through the pipes of the interior central heating system. The purpose of the article is to detail the local heat losses in case of central heating systems. Based on the conclusions of the article, we propose the modification of the calculation methodology related to the building energy audit.

scholarly journals The influence of heat loss from pipes in an unheated basement on the heating energy consumption of an entire typical apartment building

2020 ◽  
Vol 172 ◽  
pp. 12005
Author(s):  
Anti Hamburg ◽  
Targo Kalamees
Keyword(s):  
Energy Balance ◽  
Heat Loss ◽  
District Heating ◽  
Building Energy ◽  
Energy Performance ◽  
Heat Losses ◽  
Hot Water ◽  
Limited Information ◽  
Apartment Building ◽  
Heating Energy Consumption

The majority of old apartment buildings were designed with an unheated basement. Building service systems such as district heating heat exchangers and pipes for domestic hot water and for space heating are usually located in this unheated basement. In addition, these locations are connected with shafts. All these pipe’s heat losses increase air temperature in the basement. If these losses are included into the building energy balance, then they decrease heat loss through the basement ceiling. The basement’s heat balance is also dependent on heat loss from the basement envelope and outdoor air exchange in the basement. In early stages of design, designers and energy auditors need rough models to make decisions in limited information conditions. Once the effects of heat losses from pipes become apparent, they need to be factored into the buildings energy balance, and their effects on heat loss through the basement ceiling needs to be calculated. In this paper we analyse the effect these heat losses have on the service system’s heat gains and heat loss through an uninsulated basement ceiling at different basement insulation levels and with different thicknesses of pipe insulation. From our study we found that pipe losses in the basement increase the building energy performance value by at least 4 kWh/(m²∙a) and their impact on a renovated apartment building is very important.

The Combined Solar with a Dual Heat Source Heat Pump Applied in a Greenhouse Heating System - An Operation Optimization of Water Source Heat Pump

2014 ◽  
Vol 541-542 ◽  
pp. 942-948
Author(s):  
Xian Peng Sun ◽  
Zhi Rong Zou ◽  
Yue Zhang
Keyword(s):  
Heat Source ◽  
Heat Pump ◽  
Water Source ◽  
Heating System ◽  
Hot Water ◽  
Inlet Temperature ◽  
Pump System ◽  
Operation Optimization ◽  
Temperature Heat ◽  
The Impact

Based on the finite-time thermodynamic theory, an operation optimization, of water source heat pump in the combined solar with a dual heat source heat pump which is applied in a greenhouse heating system, is made. According to the ε-NTU method and entropy theory, heat exchange and balance equations are obtained. The function relationship between COP and the indoor temperature Tn, the ambient temperature Ta, low temperature heat source inlet temperature Tie and high temperature heat source inlet temperature Tic is also obtained. By means of programming, the impact of parameters on the COP and the way of regulating this water source heat pump system are presented in this article. The results show that: when a separate water source heat pump is running, by adjusting the hot water temperature and the match status of each indoor heating system, the energy-saving operation can be realized.

scholarly journals The use of substations with PCM heat accumulators in district heating system

2018 ◽  
Vol 174 ◽  
pp. 01002 ◽  
Author(s):  
Kinga Nogaj ◽  
Michał Turski ◽  
Robert Sekret
Keyword(s):  
Phase Change Materials ◽  
District Heating ◽  
Heating System ◽  
Economic Benefits ◽  
District Heating System ◽  
Save Energy ◽  
Determination Of Parameters ◽  
Storage Technologies ◽  
The Impact

The main objective of the article is to indicate the directions of development of new generations of supplying buildings with heat, by using phase change materials, referring to the technical possibilities of applying available heat storage technologies. As a detailed objective of the work, the determination of the impact of using a PCM accumulator on the temperature of the heat carrier on the return in the substation of the district heating system was adopted. Range work included determination of parameters of heat distribution network as a function of outdoor air temperature range of -20°C to +12°C. As the analysis object, the heat substation has been selected with the following parameters: supply 80°C and return 60°C. It was found that thanks to the use of PCM accumulators on heat substations, it is possible to save energy by up to approx. 6.7% and achieve economic benefits in the form of a payback period of approx. 13 years. In addition, it was found that the introduction of the PCM accumulator into the heating system allows the return temperature in the heating network to be obtained at a temperature level consistent with the adopted control table for external temperatures of the standard heating season.

scholarly journals The Impact of Load Profile on the Grid-Interaction of Building Integrated Photovoltaic (BIPV) Systems in Low-Energy Dwellings

2010 ◽  
Vol 5 (4) ◽  
pp. 137-147 ◽  
Author(s):  
R Baetens ◽  
R De Coninck ◽  
L Helsen ◽  
D Saelens
Keyword(s):  
Heating System ◽  
Hot Water ◽  
Photovoltaic System ◽  
Electricity Production ◽  
Distribution Grid ◽  
Virtual Storage ◽  
Cover Factor ◽  
Production And Consumption ◽  
Building Integrated Photovoltaic ◽  
The Impact

A building integrated photovoltaic system (BIPV) system may produce the same amount of electricity as consumed in the building on a yearly base. The simultaneity of production and consumption however needs to be evaluated: the distribution grid is regarded as virtual storage and is loaded unconventionally or even overloaded. A detailed bottom-up modelling approach of the domestic load, thermal installations and the local generation of BIPV system may give more insight. The present paper aims at quantifying the impact of domestic load profiles on the grid-interaction of BIPV-equipped dwelling in a moderate Belgian climate wherefore the cover factor is defined. For a yearly electricity production that equals the yearly domestic demand, a cover factor of 0.42 is found if a classic heating system is installed, denoting that more than half of the produced electricity will be passed on to the grid and withdrawn on another moment. If a heat pump is used for space heating and domestic hot water, the cover factor decreases to 0.29.

scholarly journals Thermal loss analysis of a solar flat collector using numerical simulation

2020 ◽  
Author(s):  
Timur Merembayev ◽  
Yedilkhan Amirgaliyev ◽  
Murat Kunelbayev ◽  
Abdumauvlen Berdyshev
Keyword(s):  
Energy Efficiency ◽  
Solar System ◽  
Heat Supply ◽  
Life Support ◽  
Heating System ◽  
Heat Losses ◽  
Hot Water ◽  
Physical Parameters ◽  
Water Heating ◽  
Solar Water Heating System

In this paper, we studied theoretically and numerically heat losses of a flat solar collector for the subsequent modelling of the solar water heating system for the Kazakhstan climate condition. For different climatic zones with a growing cost for energy or lack of central heating systems, promising is to find ways to improve the energy efficiency of the solar system. The solar system is simulated by the mathematical model (ODE model) of energy. To bridge the results of modelling and real values, our research investigated the important physical parameters such as loss coefficient, Nu, Ra, Pr values, which are impacting on the efficiency of solar flat collector and for heat losses of system. The developed mathematical models, the design and composition of the software and hardware complex, automated control and monitoring systems allow solar hot water heating system to increase the energy efficiency of a life support systems and heat supply of buildings, by reducing energy consumption for heat supply.

scholarly journals Impact of Domestic Hot Water Systems on District Heating Temperatures

Energies ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4694
Author(s):  
Tina Lidberg ◽  
Thomas Olofsson ◽  
Louise Ödlund
Keyword(s):  
Low Temperature ◽  
District Heating ◽  
Heating System ◽  
Hot Water ◽  
Space Heating ◽  
Circulation System ◽  
District Heating System ◽  
Domestic Hot Water ◽  
Temperature Levels ◽  
The Impact

When buildings become more energy effective, the temperature levels of district heating systems need to be lower to decrease the losses from the distribution system and to keep district heating a competitive alternative on the heating market. For this reason, buildings that are refurbished need to be adapted to suit low-temperature district heating. The aim of this paper is to examine whether four different energy refurbishment packages (ERPs) can be used for lowering the temperature need of a multi-family buildings space heating and domestic hot water (DHW) system as well as to analyse the impact of the DHW circulation system on the return temperature. The results show that for all ERPs examined in this study, the space heating supply temperature agreed well with the temperature levels of a low-temperature district heating system. The results show that the temperature need of the DHW system will determine the supply temperature of the district heating system. In addition, the amount of days with heating demand decreases for all ERPs, which further increases the influence of the DHW system on the district heating system. In conclusion, the DHW system needs to be improved to enable the temperature levels of a low-temperature district heating system.

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