Expediency of substitution of water heating with air heating involving use of heat pumps

2019 ◽  
Vol 12 (1) ◽  
pp. 45-49
Author(s):  
A. V. Martynov ◽  
N. E. Kutko
Keyword(s):  
Heat Pump ◽  
Ambient Air ◽  
Heat Pumps ◽  
Low Grade ◽  
Heating Season ◽  
Water Heating ◽  
Heating Systems ◽  
Air Heating ◽  
Transformation Ratio ◽  
Air Temperatures

Expediency is considered of substitution of water heating and transition to air heating that can be implemented with “air-air” type heat pumps (HP). The absence of water pipelines raises the reliability of heating systems. In addition to improved reliability, heat pumping systems ensure comfortable conditions for consumers at intervals between the heating seasons, when the central water heating is disabled.The “air-air” type HP use the ambient air as a low-grade heat source (LGHS). At low air temperatures, transformation ratio μ is about 2 and would rise to 3÷4 at higher air temperatures, which ensures high cost-efficiency of heating systems based on heat pumps. The heating season can generally be divided into two periods. One of the periods is characterized by the highest ambient air temperatures (–5÷8°С). This period is rather long and, in warmer winters, can last for about 4000 hours per heating season, or longer. This is the period, when the heat pump operates efficiently at a transformation ratio above 4.The other period, when the ambient temperature falls below –10÷ –20°С, generally lasts for a small number of hours, which makes about 15÷18% of the total duration of the heating season. At this period, the efficiency of the heat pump would decrease to μ =1.9÷2. Yet, even with such an efficiency, a heat pump delivers twice as much heat as the electric power it consumes.Therefore, in regions with a long period of temperatures within the range of –5÷8°С during a heating season, air heating based on HP can be advantageous compared to water heating.

scholarly journals Study of novel solar assisted heating system

2021 ◽  
pp. 014362442110086
Author(s):  
Gareth Davies ◽  
John Blower ◽  
Richard Hall ◽  
Graeme Maidment
Keyword(s):  
Heat Pump ◽  
Solar Collector ◽  
Computer Modelling ◽  
Low Cost ◽  
Cost Savings ◽  
Ambient Air ◽  
Heat Pumps ◽  
Heating Systems ◽  
Collector Plate ◽  
Wide Range

The potential for energy, carbon dioxide equivalent (CO2e) and cost savings when using low emissivity (low-ε) transpired solar collectors (TSCs), combined with heat pumps in a range of configurations, has been investigated using computer modelling. Low-ε TSCs consist of metal solar collector plates with a spectrally sensitive surface, perforated with holes. Ambient air is drawn through the holes and heated by convection from the solar collector plate, increasing the air temperature by up to 25 K. The heated air can be used for e.g. space heating, or pre-heating water in buildings. The models developed have been used to compare the performance of low-ε TSC/heat pump heating systems in small and large buildings, at a range of locations. The model results showed savings in energy, CO2e and costs of up to 16.4% when using low-ε TSCs combined with an exhaust air heat pump compared with using the exhaust air heat pump alone. Practical application: If the UK is to meet its target of reaching net zero greenhouse gas emissions by 2050, it will be necessary to adopt low or zero carbon heating technologies. The novel low emissivity transpired solar collector device investigated can contribute to this. Its advantages include: (i) utilising solar radiation; (ii) readily integrated with existing heating systems e.g. heat pumps; (iii) significant energy, CO2e emissions and cost savings; (iv) low cost device; (v) minimal energy input i.e. one small fan; (vi) can be retrofitted to existing buildings; (vii) its benefits were applicable at all of the (wide range of) locations tested.

scholarly journals Heat Pump Use in Rural District Heating Networks in Estonia

2021 ◽  
Vol 25 (1) ◽  
pp. 786-802
Author(s):  
Kertu Lepiksaar ◽  
Kiur Kalme ◽  
Andres Siirde ◽  
Anna Volkova
Keyword(s):  
Heat Pump ◽  
Renewable Energy Sources ◽  
District Heating ◽  
Ambient Air ◽  
Heat Pumps ◽  
Hot Water ◽  
Rural District ◽  
Low Grade ◽  
The Impact ◽  
Heating Networks

Abstract District heating has proven to be an efficient way of providing space heating and domestic hot water in populated areas. It has also proven to be an excellent way to integrate various renewable energy sources (RES) into the energy system. In Estonia, biomass covers most of the heat demand, but carbon-intensive fuels are still used to cover peaks and lows. Heat pumps can be a good solution for rural areas, as there is usually plenty of land available for heat pump facilities. In addition, heat pumps require low-grade heat sources such as ambient air, groundwater, lakes, rivers, sea, sewage water, and industrial waste heat. One of the downsides of heat pumps is the need for large investments compared to boilers fired by natural gas and biomass, and electric boilers. This study examines the impact of heat pump use on consumer prices for district heating in rural district heating networks in Estonia.

A Model for a Geothermal Well in a Hydraulic Groundwater Flow for Ground Source Heat Pump Systems

2011 ◽  
Author(s):  
Kevin D. Woods ◽  
Alfonso Ortega
Keyword(s):  
Thermal Conductivity ◽  
Analytical Solution ◽  
Groundwater Flow ◽  
Heat Pump ◽  
Temperature Response ◽  
Ambient Air ◽  
Heat Pumps ◽  
Thermal Reservoir ◽  
Geothermal Well ◽  
Ground Source

Heat pumps are mechanical systems that provide heating to a space in the winter, and cooling in the summer. They are increasingly popular because the same system provides both cooling modes, depending on the direction of the cycle upon which they operate. For proper operation, the heat pump must be connected to a constant temperature thermal reservoir which in traditional systems is the ambient air. In ground source heat pumps however, subterranean ground water is used as the thermal reservoir. To access the subterranean groundwater, “geothermal” wells are drilled into the formation. Water from the building heating or cooling system is circulated through the wells thereby promoting heat exchange between the coolant water and the subterranean formation. The potential for higher efficiency heating and cooling has increased the utilization of ground source heating ventilating and air conditioning systems. In addition, their compatibility with a naturally occurring and stable thermal reservoir has increased their use in the design of sustainable or green buildings and man-made environments. Groundwater flow affects the temperature response of thermal wells due to advection of heat by physical movement of groundwater through the aquifer. Research on this subject is scarce in the geothermal literature. This paper presents the derivation of an analytical solution for thermal dispersion by conduction and advection from hydraulic groundwater flow for a “geothermal” well. This analytical solution is validated against asymptotic analytical solutions. The traditional constant linear heat source solution is dependent on the ground formation thermal properties; the most dominant of which is the thermal conductivity. The results show that as hydraulic groundwater flow increases, the influence of the ground formation thermal conductivity on the temperature response of the well diminishes. The diminishing influence is evident in the Peclet number parameter; a comparison of thermal advection from hydraulic groundwater flow to thermal conduction by molecular diffusion.

scholarly journals  Analysis of rock mass borehole temperatures with vertical heat exchanger

2012 ◽  
Vol 58 (No. 2) ◽  
pp. 57-65 ◽  
Author(s):  
R. Adamovský ◽  
L. Mašek ◽  
P. Neuberger
Keyword(s):  
Energy Source ◽  
Rock Mass ◽  
Heat Exchanger ◽  
Heat Pump ◽  
Heat Exchangers ◽  
Heat Extraction ◽  
Heating Season ◽  
Air Temperatures ◽  
Vertical Heat ◽  
Borehole Temperatures

The goal of the article is to analyze the distribution and changes of temperatures in boreholes with the rock mass/fluid tubular heat exchangers used as an energy source for the heat pump. It also aims at documenting changes of temperatures in the rock mass during stagnation and heat extraction, and to compare the temperatures in the active and referential borehole. The testing results showed that temperatures of the rock mass reached a minimal value of 1.3°C at depths of 9 m and 20 m with maximal heat extraction corresponding to minimal air temperatures. The temperatures of the rock mass increased near the end of the heating season to values which correspond to the initial values. The temperature differences of the rock mass between the reference borehole and active boreholes increased to up to 10.5 K during the heating season. However, the temperature differences at the end of the heating season between the reference and active boreholes dropped back to 0.5–1.1 K.  

scholarly journals Seasonal coefficient of performance of air-to-air heat pump and energy performance of a building in Poland

2019 ◽  
Vol 116 ◽  
pp. 00039 ◽  
Author(s):  
Piotr Kowalski ◽  
Paweł Szałański
Keyword(s):  
Heat Pump ◽  
Energy Performance ◽  
Heat Pumps ◽  
Climatic Conditions ◽  
Coefficient Of Performance ◽  
Climatic Data ◽  
Heating Season ◽  
Season Length ◽  
Local Climate ◽  
Significant Difference

The article discusses the problem of determining for air heat pumps the seasonal efficiency of energy production necessary to determine the energy performance of a building. On the example of selected Polish cities (Suwalki, Bialystok, Warsaw, Wroclaw, Zielona Gora, Resko, Szczecinek, Koszalin) the influence of climatic conditions on the SCOP of an exemplary air-to-air heat pump and on the result of building energy performance calculations was analysed. SCOPs for each location were determined according to the method of EN 14825. The difference between SCOP for average (A) and colder (C) climates according to EN 14825 was 35.6%. It has been shown that the climate of Polish cities may be similar to both the average climate (A) and the colder climate (C), or they significantly differ from both climates. The most significant difference in SCOP between the analysed cities was obtained for Suwalki and Szczecinek. It was 31.9% and 31.4% for the assumed heating season length as for climate (A) and (C) respectively. For the exemplary building in Suwalki, taking SCOP for the average climate (A) and not based on climatic data of Suwalki gives an error of 39.3% in the calculation of primary energy for heating. For the same locations, the differences in SCOP and EP resulting from the assumption of the heating season length as for the average climate (A) or as for the colder climate (C) were respectively from 2.4% to 3.3% and from -3.4% to -2.2%. In diversified Polish climate, assuming the same SCOP values of air heat pumps regardless of location does not allow for their full comparison with devices whose efficiency does not depend on climatic conditions. The authors suggest that when calculating the energy performance of the building, the SCOP should be always determined on the basis of the local climate and the length of the heating season.

scholarly journals The modelling of reverse defrosting cycles of air-to-water heat pumps with TRNSYS

2019 ◽  
Vol 111 ◽  
pp. 01063 ◽  
Author(s):  
Matteo Dongellini ◽  
Agostino Piazzi ◽  
Filippo De Biagi ◽  
Gian Luca Morini
Keyword(s):  
Heat Pump ◽  
Operating Mode ◽  
Heat Pumps ◽  
Climatic Conditions ◽  
Performance Data ◽  
Energy Losses ◽  
Heating Season ◽  
Indoor Thermal Comfort ◽  
Reverse Mode ◽  
Heating Capacity

The most widespread defrosting technique adopted by Air-Source Heat Pumps (ASHPs) during the heating season is Reverse Cycle Defrosting (RCD). In this paper a dynamic model of RCD, based on performance data provided by the heat pump manufacturer, designed for TRNSYS and with a core-structure suitable for commercial units, is presented. A defrost cycle is divided in three phases. First, the unit heating capacity is reduced as a linear function of the ice layer thickness (Pre-Defrost phase). Subsequently, the reverse cycle operating mode is modelled on the basis of the performance data given by the manufacturer (Defrost phase) and, finally, the heat pump performances are altered taking into account the higher surface temperature of the external coil after the reverse mode (Post-Defrost phase). Then, the influence of defrosting energy losses on the heat pump seasonal performance factor in sites characterized by different climatic conditions has been assessed. Results point out that the ASHP seasonal efficiency decreases of about 5% taking into account defrost energy losses; in addition, the influence of defrost cycles on the internal air temperature is studied by assessing under which conditions the indoor thermal comfort can be guaranteed even in presence of frequent defrost cycles.

Simulation of hybrid ground-coupled heat pump with domestic hot water heating systems using HVACSIM+

2008 ◽  
Vol 40 (9) ◽  
pp. 1731-1736 ◽  
Author(s):  
Ping Cui ◽  
Hongxing Yang ◽  
Jeffrey D. Spitler ◽  
Zhaohong Fang
Keyword(s):  
Heat Pump ◽  
Hot Water ◽  
Water Heating ◽  
Heating Systems ◽  
Domestic Hot Water ◽  
Ground Coupled Heat Pump

scholarly journals Hybrid system solar collectors - heat pumps for domestic water heating

2019 ◽  
Vol 23 (6 Part A) ◽  
pp. 3675-3685
Author(s):  
Simon Marcic ◽  
Rebeka Kovacic-Lukman ◽  
Peter Virtic
Keyword(s):  
Solar Radiation ◽  
Flat Plate ◽  
Heat Pump ◽  
Autonomous System ◽  
Identical Condition ◽  
Heat Pumps ◽  
Hot Water ◽  
Water Heating ◽  
Domestic Water ◽  
Flat Plate Collector

This paper deals with the use of solar energy, heat pumps, and solar system-heat pump combinations for domestic water heating. The testing of solar tiles, flat plate collectors as an autonomous system, as well as flat plate collector-heat pump and solar tile-heat pump combinations, are presented. Black-coloured water absorbs solar radiation flows through solar tiles made of transparent polymethyl methacrylate (CH2C(CH3)COOCH3). At the same time, solar tiles are used as a roof covering and as a solar radiation collector. Hot water from solar tiles or a flat plate collector is directed to the heat pump, which increases the temperature of water entering the boiler heating coil. The heat of water heated in solar tiles or in flat plate collectors serves as a source of energy for the heat pump. Since the goal was realistically evaluate the efficiency of solar tiles in comparison with the flat plate collector, extensive measurements of both systems under identical condition were carried out. The experiments were carried out in rainy, cloudy, and clear weather.

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