scholarly journals Optimal Operation of Low-Capacity Heat Pump Systems for Residential Buildings through Thermal Energy Storage

2021 ◽  
Vol 13 (13) ◽  
pp. 7200
Author(s):  
Alessandro Franco ◽  
Carlo Bartoli ◽  
Paolo Conti ◽  
Daniele Testi
Keyword(s):  
Heat Pump ◽  
Residential Buildings ◽  
Electric Energy ◽  
Thermal Storage ◽  
High Water ◽  
Energy Performance ◽  
Heat Emission ◽  
Optimal Operation ◽  
Pump Operation ◽  
In Series

The paper provides results from a hardware-in-the-loop experimental campaign on the operation of an air-source heat pump (HP) for heating a reference dwelling in Pisa, Italy. The system performances suffer from typical oversizing of heat emission devices and high water-supply temperature, resulting in HP inefficiencies, frequent on-off cycles, and relevant thermal losses on the hydronic loop. An experimentally validated HP model under different supply temperatures and part-load conditions is used to simulate the installation of a thermal storage between heat generator and emitters, in both series and parallel arrangements. Results relative to a typical residential apartment show that the presence of the thermal storage in series configuration ensures smoother heat pump operation and energy performance improvement. The number of daily on-off cycles can be reduced from 40 to 10, also saving one-third of electric energy with the same building loads. Preliminary guidelines are proposed for correctly sizing the tank in relation to the HP capacity and the average daily heating load of the building. A storage volume of about 70 L for each kilowatt of nominal heating capacity is suggested.

scholarly journals Waste Heat Recovery by Air-to-Water Heat Pump from Exhausted Ventilating Air for Heating of Multi-Family Residential Buildings

Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7985
Author(s):  
Piotr Kowalski ◽  
Paweł Szałański ◽  
Wojciech Cepiński
Keyword(s):  
Heat Pump ◽  
Waste Heat ◽  
Residential Buildings ◽  
Heating System ◽  
Energy Performance ◽  
Design Parameters ◽  
Pump Operation ◽  
System Parameters ◽  
Temperature Limitation ◽  
The Impact

The paper presents an analysis of the application of an air-to-water electric compressor heat pump (AWHP) for the recovery of waste heat from the exhaust air in a typical multifamily residential building and the use of this heat for space heating, as well as the impact of this solution on the building energy performance (the PPR index). Simulations were performed in TRNSYS for five locations in Poland (Koszalin, Wrocław, Lublin, Białystok, Suwałki), for various heating system parameters (80/60 °C, 75/65 °C, 70/50 °C, 55/45 °C, 35/28 °C), for various temperature limitations of heat pump operation. It was shown that the analyzed system has great potential from an energy and environmental point of view. It can provide significant benefits in terms of the energy performance of the building, depending on the system parameters. The results show that the most energy-efficient system is the one with the lowest heating system temperatures. Moreover, implementing a temperature limitation on the heat pump operation improves its efficiency, but the higher the design parameters of the heating installation and the lower the limitation, the lower the heat pump contribution, and the higher the SCOP and the PPR. The energy effect is also influenced by location, but its scale depends on the parameters of the heating system and the temperature limitation of the heat pump’s operation. It is more significant for lower heating system parameters. This system enables the possibility of further reducing the demand for nonrenewable primary energy by powering the heat pump with photovoltaic cells.

scholarly journals Performance Analysis of Air-to-Water Heat Pump in Latvian Climate Conditions

2014 ◽  
Vol 14 (1) ◽  
pp. 18-22 ◽  
Author(s):  
Janis Kazjonovs ◽  
Andrejs Sipkevics ◽  
Andris Jakovics ◽  
Andris Dancigs ◽  
Diana Bajare ◽  
...  
Keyword(s):  
Heat Pump ◽  
Air Temperature ◽  
Residential Buildings ◽  
Winter Season ◽  
Pump Energy ◽  
Energy Performance ◽  
Coefficient Of Performance ◽  
Heating Period ◽  
Climate Conditions ◽  
Eu Directive

Abstract Strategy of the European Union in efficient energy usage demands to have a higher proportion of renewable energy in the energy market. Since heat pumps are considered to be one of the most efficient heating and cooling systems, they will play an important role in the energy consumption reduction in buildings aimed to meet the target of nearly zero energy buildings set out in the EU Directive 2010/31/EU. Unfortunately, the declared heat pump Coefficient of Performance (COP) corresponds to a certain outdoor temperature (+7 °C), therefore different climate conditions, building characteristics and settings result in different COP values during the year. The aim of this research is to investigate the Seasonal Performance factor (SPF) values of air-to-water heat pump which better characterize the effectiveness of heat pump in a longer selected period of time, especially during the winter season, in different types of residential buildings in Latvian climate conditions. Latvia has four pronounced seasons of near-equal length. Winter starts in mid-December and lasts until mid-March. Latvia is characterized by cold, maritime climate (duration of the average heating period being 203 days, the average outdoor air temperature during the heating period being 0.0 °C, the coldest five-day average temperature being −20.7 °C, the average annual air temperature being +6.2 °C, the daily average relative humidity being 79 %). The first part of this research consists of operational air-towater heat pump energy performance monitoring in different residential buildings during the winter season. The second part of the research takes place under natural conditions in an experimental construction stand which is located in an urban environment in Riga, Latvia. The inner area of this test stand, where air-to-water heat pump performance is analyzed, is 9 m2. The ceiling height is 3 m, all external wall constructions (U = 0.16 W/(m2K)) have ventilated facades. To calculate SPF, the experimental stand is equipped with sensors which provide measurements for electricity consumption and gained heat energy.

scholarly journals Investigation of Heat Pump Operation Strategies with Thermal Storage in Heating Conditions

Energies ◽  
2017 ◽  
Vol 10 (12) ◽  
pp. 2020 ◽  
Author(s):  
Wangsik Jung ◽  
Dongjun Kim ◽  
Byung Kang ◽  
Young Chang
Keyword(s):  
Heat Pump ◽  
Thermal Storage ◽  
Pump Operation

scholarly journals Combinations of heat pump and photovoltaics for renovated buildings

2019 ◽  
Vol 111 ◽  
pp. 01003
Author(s):  
Andreas Heinz ◽  
Christian Gaber
Keyword(s):  
Heat Pump ◽  
Residential Buildings ◽  
Electrical Energy ◽  
Heating System ◽  
Heat Emission ◽  
Single Family ◽  
Pv System ◽  
Air Source Heat Pump ◽  
Emission System ◽  
Family House

The aim of this work is the analysis of hybrid heating systems consisting of an air source heat pump, a storage tank and a photovoltaic (PV) system for the use in renovated residential buildings. The potential for decreasing the electrical energy consumption of the heat pump from the grid by targeted operation of the speed controlled compressor with electricity from PV is determined by means of dynamic system simulations in TRNSYS for a renovated single family house under the assumption that the existing radiator heating system is not replaced, and that therefore relatively high supply temperatures are necessary. Different variants were considered with regard to the size of the PV system, the storage volume and the influence of the heat emission system.

scholarly journals Integration of Micro-Cogeneration Units and Electric Storages into a Micro-Scale Residential Solar District Heating System Operating with a Seasonal Thermal Storage

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5456
Author(s):  
Antonio Rosato ◽  
Antonio Ciervo ◽  
Giovanni Ciampi ◽  
Michelangelo Scorpio ◽  
Sergio Sibilio
Keyword(s):  
Natural Gas ◽  
Residential Buildings ◽  
Electric Energy ◽  
District Heating ◽  
Thermal Storage ◽  
Hot Water ◽  
District Heating System ◽  
Domestic Hot Water ◽  
Micro Scale ◽  
Gas Fueled

A micro-scale district heating network based on the operation of solar thermal collectors coupled to a long-term borehole thermal storage is modeled, simulated and investigated over a period of five years. The plant is devoted to covering the domestic hot water and space heating demands of a district composed of six typical residential buildings located in Naples (southern Italy). Three alternative natural gas-fueled back-up auxiliary systems (condensing boiler and two different technologies of micro-cogeneration) aiming at balancing the solar energy intermittency are investigated. The utilization of electric storages in combination with the cogeneration systems is also considered with the aim of improving the self-consumption of cogenerated electric energy; heat recovery from the distribution circuit is also evaluated to pre-heat the mains water for domestic hot water production. The performances of the proposed plant schemes are contrasted with those of a typical Italian decentralized heating plant (based on the utilization of natural gas-fueled non-condensing boilers). The comparison highlighted that the proposed configurations can decrease the primary energy consumption (up to 11.3%), the equivalent emissions of carbon dioxide (up to 11.3%), and the operation costs (up to 14.3%), together with an acceptable simple pay-back period (about 4.4 years).

scholarly journals Numerical Analysis and Preliminary Experiment of a Solar Assisted Heat Pump Drying System for Chinese Wolfberry

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4306 ◽  
Author(s):  
Zhongting Hu ◽  
Sheng Zhang ◽  
Wenfeng Chu ◽  
Wei He ◽  
Cairui Yu ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Heat Pump ◽  
Electric Energy ◽  
Energy Performance ◽  
Operating Conditions ◽  
Pump System ◽  
Heat Pump System ◽  
Electric Energy Consumption ◽  
Drying System ◽  
Heat Pump Drying

The present work investigated a solar assisted heat pump system for drying Chinese wolfberry. The kinetic characteristic was firstly analyzed through a series of lab experiments. It was concluded that the Page model was the most suitable for predicting the heat and mass transfer of the wolfberry. Based on the wolfberry kinetic model, solar collector model and chamber air model, the coupled drying system model was developed. The accuracy of the mathematic model was determined through comparing with the preliminary experimental results. The influence of operating conditions on the thermal and energy performance of the dryer for the different operating mode was discussed. The drying weight of no more than 75 kg may be preferable in the stand-alone solar drying mode, and less than 15 h was needed to be dried. The electric energy consumption in the solar assisted the heat pump drying mode was lower than that in the stand-alone heat pump mode, and it was recommended that about 50 kg of wolfberry to be dried in the solar assisted heat pump system. Compared to the autumn drying, the reduction in the electric energy consumption was around 9.1 kWh during the 11 h summer drying process. The obtained results demonstrated the feasibility of the combined system for drying wolfberry, and also can provide the basic theoretical and experimental data support for the following research.

Aqueous Lithium Bromide TES and R-123 Chiller in Series

2003 ◽  
Vol 125 (1) ◽  
pp. 49-54 ◽  
Author(s):  
J. J. Rizza
Keyword(s):  
Heat Pump ◽  
Liquid Water ◽  
Lithium Bromide ◽  
Water System ◽  
Internal Heat ◽  
Thermal Storage ◽  
Volumetric Efficiency ◽  
Peak Period ◽  
Water Ice ◽  
In Series

This paper presents an analysis of a cold thermal energy storage (TES) system operating in series with an R-123 chiller. A lithium bromide/water LiBr/H2O solution is used both as a refrigerant and as a cold thermal storage material. The refrigerant, liquid water, is extracted from the LiBr/H2O strong solution during the off-peak period. The liquid water and LiBr/H2O weak solution, a byproduct of the refrigerant recovery process, are used during the on-peak period to cool the building. Building waste heat is pumped by the R-123 compressor to a higher temperature during the off-peak period and is used in the generator to recover the thermal storage by reprocessing the stored solution to a higher lithium bromide concentration. The storage volumetric efficiency and system COP are determined and compared to storage systems based on water/ice and liquid water. The storage volumetric efficiency is greater than a water/ice system and far exceeds the value for a liquid water system. The proposed system, which uses an external heat pump as a source of generator heat, is also compared to another LiBr/H2O system that uses a self-contained internal heat pump (the compressor operates independently from the chiller and uses the liberated water refrigerant as its working fluid). The system presented here outperforms both the water/ice system and the internal heat pump LiBr/H2O system but is unable to match the liquid water system COP. However, it has other well-defined advantages over the liquid water system and appears to be a competitive alternative to conventional TES systems.

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