scholarly journals Energy Analysis of a Dual-Source Heat Pump Coupled with Phase Change Materials

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2933
Author(s):  
Michele Bottarelli ◽  
Francisco Javier González Gallero

Installation costs of ground heat exchangers (GHEs) make the technology based on ground-coupled heat pumps (GCHPs) less competitive than air source heat pumps for space heating and cooling in mild climates. A smart solution is the dual source heat pump (DSHP) which switches between the air and ground to reduce frosting issues and save the system against extreme temperatures affecting air-mode. This work analyses the coupling of DSHP with a flat-panel (FP) horizontal GHE (HGHE) and a mixture of sand and phase change materials (PCMs). From numerical simulations and considering the energy demand of a real building in Northern Italy, different combinations of heat pumps (HPs) and trench backfill material were compared. The results show that PCMs always improve the performance of the systems, allowing a further reduction of the size of the geothermal facility. Annual average heat flux at FP is four times higher when coupled with the DSHP system, due to the lower exploitation. Furthermore, the enhanced dual systems are able to perform well during extreme weather conditions for which a sole air source heat pump (ASHP) system would be unable either to work or perform efficiently. Thus, the DSHP and HGHE with PCMs are robust and resilient alternatives for air conditioning.

Energies ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2496 ◽  
Author(s):  
Laura Carnieletto ◽  
Borja Badenes ◽  
Marco Belliardi ◽  
Adriana Bernardi ◽  
Samantha Graci ◽  
...  

The design of ground source heat pumps is a fundamental step to ensure the high energy efficiency of heat pump systems throughout their operating years. To enhance the diffusion of ground source heat pump systems, two different tools are developed in the H2020 research project named, “Cheap GSHPs”: A design tool and a decision support system. In both cases, the energy demand of the buildings may not be calculated by the user. The main input data, to evaluate the size of the borehole heat exchangers, is the building energy demand. This paper presents a methodology to correlate energy demand, building typologies, and climatic conditions for different types of residential buildings. Rather than envelope properties, three insulation levels have been considered in different climatic conditions to set up a database of energy profiles. Analyzing European climatic test reference years, 23 locations have been considered. For each location, the overall energy and the mean hourly monthly energy profiles for heating and cooling have been calculated. Pre-calculated profiles are needed to size generation systems and, in particular, ground source heat pumps. For this reason, correlations based on the degree days for heating and cooling demand have been found in order to generalize the results for different buildings. These correlations depend on the Köppen–Geiger climate scale.


Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1966
Author(s):  
Gábor L. Szabó

This paper presents the results of energy analysis of absorption heat pumps. The thermo-chemical instability term was introduced for absorption heat pumps used for heating or cooling or heating and cooling. A higher thermo-chemical instability results in the equipment being more sensitive with regard to the variation of the heat source flux. This sensitivity can be taken into account when heat sources are chosen for a certain absorption machine. Absorption heat pumps having thermo-chemical compressors were compared from energy demand and energy efficiency points of view with heat pumps having mechanical compressors. As it is shown, for certain evaporation and condensation temperature values, an absorption heat pump with similar efficiency to that of the heat pump with a mechanical compressor can always be found.


Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6287
Author(s):  
Lazaros Aresti ◽  
Paul Christodoulides ◽  
Gregoris P. Panayiotou ◽  
Georgios Florides

Shallow Geothermal Energy Systems (SGESs) constitute Renewable Energy Systems (RES), which find application in the residential sector through the use of Ground Source Heat Pumps (GSHPs). GSHPs are associated with Ground Heat Exchangers (GHEs), whereby heat is gained/lost through a network of tubes into the ground. GSHPs have failed to flourish in the RES market due to their high initial costs and long payback periods. In this study, the use of Energy Geo-Structure (EGS) systems, namely, the foundation (or energy) piles and the foundation bed of a residential building in Cyprus, was computationally modeled in the COMSOL Multiphysics software. First, the single-houses’ trend in number of units and area in Cyprus was examined and a theoretically typical house with nearly Zero Energy Building (nZEB) characteristics was considered. The heating and cooling loads were estimated in the TRNSYS software environment and used as inputs to investigate the performance of the GSHP/GHE systems. Both systems were shown to exhibit steady performance and high Coefficient of Performance (COP) values, making them an alternative RES solution for residential building integration. Next, the systems were economically evaluated through a comparison with a convectional Air Source Heat Pump (ASHP) system. The economic analysis showed that the cost of the suggested conversions of the foundation elements into GHEs had short payback periods. Consequently, either using the foundation piles or bed as a GHE is a profitable investment and an alternative to conventional RES.


Proceedings ◽  
2020 ◽  
Vol 51 (1) ◽  
pp. 11
Author(s):  
Agata Witkowska ◽  
Dorota Anna Krawczyk

In recent years, modern and energy-saving solutions, such as heat pumps or solar collectors, have enjoyed great popularity in the heating and cooling sector, which is conditioned by political and environmental factors. The aim of this paper was to analyze the advisability of the employment of renewable energy sources, such as a heat pump, for heating and cooling in single-family buildings in Poland and Spain. Based on the calculations made for a traditional house, located in two cities with different climatic conditions—Wroclaw and Cordoba, the heat losses and gains were determined. On that basis, the heating and cooling demand for these locations were calculated and next—taking into account the obtained results—reversible air–water heat pumps were selected. In addition, the investment expenditures for purchase and assembly of the heat pumps were estimated, as well as the operating costs of the installation. After a deep analysis, it was found that the total cost of using an air-source heat pump, is almost 44% lower for Cordoba, than for Wroclaw.


Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5263
Author(s):  
Miguel Ángel Álvarez-Feijoo ◽  
Pedro Orgeira-Crespo ◽  
Elena Arce ◽  
Andrés Suárez-García ◽  
José Roberto Ribas

Airports, broadly spread world-wide, present continuously increasing energy demands for heating and cooling purposes. Relocatable facilities within them could be built on recycling shipping containers provided with the right insulation layer, to reduce the outstanding consumption of the heating, ventilation and air conditioning systems (HVAC). This research focuses on studying the effect of added insulation on the thermal performance of a construction in the scope of an airport facility, based on a recycled shipping container. Passive heating and cooling insulation strategies have shown good results in terms of energy savings. A series of simulations were performed along six different Spanish airports locations, selected to represent several climate conditions. Temperature evolution inside the container, and energy demands of the HVAC system were obtained to show that the insulation provided by phase change materials (PCM) is performing better than traditional insulation, or a raw container. Although there are slight behavior differences according to the climate, PCM can increase inside temperature even with no HVAC under certain circumstances.


Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 2971
Author(s):  
Rok Koželj ◽  
Eneja Osterman ◽  
Fabrizio Leonforte ◽  
Claudio Del Pero ◽  
Alessandro Miglioli ◽  
...  

When considering the deployment of renewable energy sources in systems, the challenge of their utilization comes from their time instability when a mismatch between production and demand occurs. With the integration of thermal storages into systems that utilize renewable energy sources, such mismatch can be evened out. The use of phase-change materials (PCMs) as thermal storage has a theoretical advantage over the sensible one because of their high latent heat that is released or accumulated during the phase-change process. Therefore, the present paper is a review of latent thermal storages in hydronic systems for heating, cooling and domestic hot water in buildings. The work aims to offer an overview on applications of latent thermal storages coupled with heat pumps and solar collectors. The review shows that phase-change materials improve the release of heat from thermal storage and can supply heat or cold at a desired temperature level for longer time periods. The PCM review ends with the results from one of the Horizon2020 research projects, where indirect electrical storage in the form of thermal storage is considered. The review is a technological outline of the current state-of-the-art technology that could serve as a knowledge base for the practical implementation of latent thermal storages. The paper ends with an overview of energy storage maturity and the objectives from different roadmaps of European bodies.


2019 ◽  
Vol 11 (1) ◽  
pp. 122-130
Author(s):  
Sandra Budžaki ◽  
Jozo Leko ◽  
Kristina Jovanović ◽  
Jožef Viszmeg ◽  
Ivo Koški

Drying as one of the oldest food preservation processes is also the most energy demanding process. Nowadays, when conventional energy sources are declining, reduction/rationalization of energy consumptions in industrial processes is of great importance. One of the more successful ways of saving energy and make the process energy efficient is the integration of heat pumps within the existing technological processes. Heat pump systems are successfully used for different applications such as heating and cooling, and drying as well. In addition, the quality of final dried product is a priority that can be accomplished by heat pump assisted drying systems. This paper presents up-to-date survey in the field of air source heat pump assisted drying of food: fruit, vegetables, herbs and spices.


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