scholarly journals Air-source heat pump performance comparison in different real operational conditions based on advanced exergy and exergoeconomic approach

2020 ◽  
pp. 237-237
Author(s):  
Goran Vuckovic ◽  
Mirko Stojiljkovic ◽  
Marko Ignjatovic ◽  
Mica Vukic

The use of air-source heat pumps (ASHP) is increasing to meet the energy needs of residential buildings, and manufacturers of equipment have permanently expanded the range of work and improved the coefficient of performance (COP) in very adverse outdoor air conditions. However, in the time of a wide range of different technologies, the problem of using ASHP, from a techno-economic point of view, is constantly present. Although exergy is the only thermodynamic parameter compatible with economic principles, methods based on conventional exergy analysis are no longer able to respond to the extremely demanding needs of the actual market. Exergetic efficiency and exergoeconomic cost no longer provide sufficiently reliable information when it is necessary to reduce the investment costs or increase the energy/exergetic efficiency of the component/system. This paper presents a performance comparison of ASHP in different real operational conditions based on an advanced exergy and exergoeconomic approach. The advanced exergy analysis splits the destruction of exergy for each individual component of the heat pump into avoidable and unavoidable exergy destruction in order to fully understand the processes. In exergoeconomic performance evaluation, the information of stream costs is used as the information to calculate exergoeconomic variables associated with each system component. Irreversibilities in the compressor have the greatest impact on reducing the overall system exergetic efficiency by 46.7% during underfloor heating (UFH) operation and 24.53% during domestic hot water (DHW) operation. Exergy loss reduces exergetic efficiency by 5.72% (UFH) and 39.74% (DHW). High values of exergoeconomic cost for both operating regimes are present in flows 1, 2, 3 and 4 due to high costs of production and relatively small exergy levels. The general recommendation is to set the ASHP to operate with near-optimal capacities in both regimes and then reduce exergy of flows 1, 2, 5, 11 and 13.

Author(s):  
Norbert Ka¨mmer

Heat pumps for residential space heating has become an increasingly important alternative to the conventional European heating systems like gas or oil burners. They offer the opportunity to reduce CO2 emission associated with heating residential homes in central and northern Europe as well as energy savings. The operational parameters for compressors in heat pumps are derived from different heat pump configurations. High compressor efficiency and a wide operating map is required so that an economically viable heat pump is achieved which meets the required operational conditions. The modifications to the basic refrigeration scroll compressor design are demonstrated. These dedicated compressor designs make it possible to achieve the required high condensing temperatures. A performance comparison with the standard compressor designs is presented and the available product range for the design of heat pump systems is shown.


2019 ◽  
Vol 111 ◽  
pp. 03025
Author(s):  
Annamaria Belleri ◽  
Chiara Dipasquale ◽  
Jennifer Adami

Despite a wide range of energy-efficient technologies, financial products and public incentives are already available, the private as well as the public sector are struggling to invest in energy efficient solutions for buildings. The primary barriers are the high initial cost and the uncertain payback period of the energy refurbishment. Allowing for different scenario testing and considering interactions among different building energy systems, building energy simulation tools can help investors overcoming such barriers by offering support to the technical planning of energy refurbishment kits through quantitative information rather than qualitative. The energy performance and comfort of three reference multifamily residential buildings typologies were evaluated considering three envelope retrofitting performance levels (high-medium-low insulated and airtight) and different heating and domestic hot water systems (heat pump, boiler, district heating). The tested envelope retrofitting performance levels allow for heating need reduction between 50% and 90% compared to the reference case. The active cooling system is not accounted for and building energy simulations outputs include thermal comfort evaluation and overheating risk assessment during the summer season. The potential of photovoltaic system combined with heat pump is evaluated in the three reference cases leading to up to 30% of load coverage.


Author(s):  
Jenny Chu ◽  
Cynthia A. Cruickshank

Heat pumps are commonly used for space-heating and cooling requirements. The combination of solar thermal and heat pump systems as a single solar-assisted heat pump (SAHP) system is a promising technology for offsetting domestic hot water, space-heating and cooling loads more efficiently. Task 44 of the Solar Heating and Cooling Programme of the International Energy Agency is currently investigating ways to optimize SAHP systems for residential use. This paper presents a review of past and current work conducted on SAHP systems. Specifically, the key performance data from many studies are highlighted and different system configurations are compared in order to establish insight towards which system configurations are suitable for the Canadian residential sector. It was found that the most suitable configuration for Canadian residential buildings depend on a combination of factors which may include occupant behavior, building characteristics, operation parameters, system components, the performance criteria of interest and climate. A large variety of configurations and parameters exist for SAHP systems and this made analyzing a specific system, comparing differing systems and establishing an optimal design fairly difficult. It was found that different authors used various different performance criterions and this inconsistency also added to the difficulty of comparing the studies of different systems. Overall, a standard performance criterion needs to be established for SAHP systems in order to meaningfully compare different configurations and determine optimal configurations for certain requirements.


2021 ◽  
Author(s):  
Afarin Amirirad

Considering the large energy consumption of conventional water heaters in residential buildings, the performance of a new type of water heater has been characterized through conducting experiments and numerical modelling. The specific water heater investigated in this work benefits from heat absorption from the indoor air, denoted as the air source heat pump water heater (ASHPWH), and is located in the Archetype Sustainable Twin House B in Toronto. The experiments have been conducted under three different indoor conditions associated with temperature and humidity. The coefficient of performance (COP), which quantifies the ratio of heating capacity to the consumed power of ASHPWH, ranges between 1.5 and 5, depending on the indoor dry bulb and water inlet temperatures. A TRNSYS model of ASHPWH has been constructed based on the obtained experimental results and has subsequently been integrated with a TRNSYS model of the Archetype Sustainable House (ASH). The numerical results were verified with the experimental data. The model results suggests that after employing ASHPWH, the domestic hot water energy consumption reduces by 60.3% and 53.2% compared to the electric water heater in summer and winter respectively. Due to the energy absorption of ASHPWH from the indoor environment, the heating load of the ASH house increases while its cooling load decreases. Furthermore, the annual electricity consumption of the ASH house due to the required heating and cooling as well as the domestic hot water demand is reduced by 21.3%. Finally, as a consequence of employing ASHPWH, the energy cost and GHG emission were reduced respectively by 22% and 21.7%. By investigating the system in four other Canadian cities, it appears that Vancouver and Edmonton would have the maximum and minimum energy savings respectively.


2021 ◽  
Author(s):  
Afarin Amirirad

Considering the large energy consumption of conventional water heaters in residential buildings, the performance of a new type of water heater has been characterized through conducting experiments and numerical modelling. The specific water heater investigated in this work benefits from heat absorption from the indoor air, denoted as the air source heat pump water heater (ASHPWH), and is located in the Archetype Sustainable Twin House B in Toronto. The experiments have been conducted under three different indoor conditions associated with temperature and humidity. The coefficient of performance (COP), which quantifies the ratio of heating capacity to the consumed power of ASHPWH, ranges between 1.5 and 5, depending on the indoor dry bulb and water inlet temperatures. A TRNSYS model of ASHPWH has been constructed based on the obtained experimental results and has subsequently been integrated with a TRNSYS model of the Archetype Sustainable House (ASH). The numerical results were verified with the experimental data. The model results suggests that after employing ASHPWH, the domestic hot water energy consumption reduces by 60.3% and 53.2% compared to the electric water heater in summer and winter respectively. Due to the energy absorption of ASHPWH from the indoor environment, the heating load of the ASH house increases while its cooling load decreases. Furthermore, the annual electricity consumption of the ASH house due to the required heating and cooling as well as the domestic hot water demand is reduced by 21.3%. Finally, as a consequence of employing ASHPWH, the energy cost and GHG emission were reduced respectively by 22% and 21.7%. By investigating the system in four other Canadian cities, it appears that Vancouver and Edmonton would have the maximum and minimum energy savings respectively.


Author(s):  
Michael J. Kazmierczak ◽  
Abhishek Gupta

Experiments were performed on a heat exchanger equipped with multiple thermoelectric (TE) modules. The TE-HX serves as the basic system component in a simple hydronic modular Peltier heat pump system designed to provide chilled or hot water for domestic use (or supplementary building climate control) of small residences [1]. The present work focuses on the detailed convection analysis inside the TE-HX component when 10 thermoelectric modules are utilized. The local heat transfer coefficient at different points along the channel are measured at steady-state, first, when a continuous heater is installed and then when replaced with 10 TE modules. The experimental heat transfer coefficients obtained are compared with available empirical correlations for “transition” (3000 < ReDh < 7000) turbulent flow inside the channel with fair-to-good results. Next, the resulting coefficient-of-performance of the TE heat pump system is measured with its value depending both on system input power and water flow rate. Testing showed that performance degradation, i.e. reduced COPs, occurred when operated at higher power levels but remains satisfactory for up to 688 Watts with higher flow rate.


Author(s):  
Shuang Lu ◽  
Jingyi Wu

In Chinese market, many homes use heat pump systems for heating and cooling. Domestic hot water is usually provided by a domestic water heater making use of electricity, natural gas or solar energy, which is known for its great energy costs. These systems consume much energy and increase the total cost of the required domestic energy. A new system combining heat pump with water heater is proposed in this paper, and it is named domestic energy system. The system can realize the provision of space heating, cooling and domestic hot water throughout the year. Based on the different types of heat pumps and water heaters, domestic energy consumption patterns are divided into five categories: heat pump and gas-fired water heater system, heat pump and solar water heater system, heat pump and electricity water heater system, heat pump and heat pump water heater system, and domestic energy system. This study describes and compares all of the above-mentioned systems including energy and exergy analysis. Results showed that the domestic energy system can save energy and provide good economy.


Author(s):  
Michael J. Kazmierczak ◽  
Sreenidhi Krishnamoorthy ◽  
Abhishek Gupta

Experiments were performed to charge either cold or hot water thermal energy storage tanks using a heat exchanger equipped with multiple thermoelectric (TE) modules. The primary objective was to design a simple, but effective, modular Peltier heat pump system component to provide chilled or hot water for domestic use at the appliance level, and when arranged in multiple unit combinations, a system that can potentially satisfy small home cooling and heating requirements. Moreover, when the TEs are directly energized using solar PV panels, the system provides a renewable, pollution free and off-the-grid solution to supplement home energy needs. The present work focuses on the design and testing of a thermoelectric heat exchanger component that consists of two water channels machined from two aluminum plates with an array of three or five thermoelectric modules placed in between to transiently cool and/or heat the water in the thermal energy storage tank. The water passing over either the cold or hot side of the TE modules is recirculated to charge the cold or hot thermal storage tank, respectively. The temperatures in the prototype Peltier heat exchanger test component and thermal energy water storage tank were measured during both cold tank charging and hot tank charging operation. The thermal efficiencies of TE heat pump cooling/heating system are reported. The effects of TE power input, number of TE units and rate of fluid flow are studied.


Author(s):  
Wessam El-Baz ◽  
Peter Tzscheutschler ◽  
Ulrich Wagner

There is a continuous growth of heat pump installations in residential buildings in Germany. The heat pumps were not only used for space heating and domestic hot water consumption but also to offer flexibility to the grid. the high coefficient of performance and the low cost of heat storages made the heat pumps an optimal candidate for the power to heat applications. Thus, several questions are raised about the optimal integration and control of the heat pump system with buffer storages to maximize its operation efficiency and minimize the operation costs. In this paper, an experimental investigation is performed to study the performance of a ground source heat pump (GSHP) with a combi-storage under several configurations and control factors. The experiments were performed on an innovative modular testbed that is capable of emulating a ground source to provide the heat pump with different temperature levels at different times of the day. Moreover, it can emulate the different building loads such as the space heating load and the domestic hot water consumption in real-time. The data gathered from the testbed and different experimental studies were used to develop a simulation model based on Modelica that can accurately simulate the dynamics of a GSHP in a building. The model was validated based on different metrics. Energetically, the difference between the developed model and the measured values was only 3.08\% and 4.18\% for the heat generation and electricity consumption, respectively.


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