energies-logo

Journal Browser

Journal Browser

Design of Heat Exchangers for Heat Pump Applications

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "J: Thermal Management".

Deadline for manuscript submissions: closed (31 May 2020) | Viewed by 23553

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editors

Dime Department of Mechanical, Energy, Management and Transportation Engineering, The University of Genova, via Opera Pia 15, 16145 Genova, Italy
Interests: ground source heat pumps; borehole heat exchangers; ground modelling; thermal response test; advanced equipment and sensors for geothermal heat pumps; temperature response factor estimation; ground heat exchanger design and criteria; energy pile heat exchangers
Special Issues, Collections and Topics in MDPI journals
Dime Department of Mechanical, Energy, Management and Transportation Engineering, The University of Genova, via Opera Pia 15, 16145 Genova, Italy
Interests: ground coupled heat pumps; energy in buildings; heat transfer; renewable energy
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

It is our pleasure to invite you to submit a paper for a Special Issue of Energies on the topic of "Design of Heat Exchangers for Heat Pump Applications".

As is well known, heat pumps (HPs) allow for providing heat without direct combustion, in both civil and industrial applications. They are very efficient systems that, by exploiting electrical energy, greatly reduce local environmental pollution and CO2 global emissions. The fact that electricity is a partially renewable resource and because the coefficient of performance (COP) can be as high as four or more, means that HPs can be nearly carbon neutral for a full sustainable future.

The proper selection of the heat source and the correct design of the heat exchangers is crucial for attaining high HP efficiencies—examples can be ground coupled heat exchangers, lake/sea/waste water systems, enhanced surface heat exchangers, and HPs exploiting waste heat from industrial and civil processes.

Heat exchangers (also in terms of HP control strategies) are hence one of the main elements of HPs, and improving their performance enhances the effectiveness of the whole system. Both the heat transfer and pressure drop have to be taken into account for the correct sizing, especially in the case of mini- and micro-geometries, for which traditional models and correlations can not be applied. New models and measurements are required for best HPs system design, including optimization strategies for energy exploitation, temperature control, and mechanical reliability. A relevant feature is also the phase change of the refrigerant, which can involve problems related to the phase distribution in the heat exchanger.

Moreover, the selection of the proper refrigerant fluid it is important in order to improve the energy performance and to enhance environmental compatibility. Thus, a multidisciplinary approach of the analysis is requested.

Papers submitted for this Special Issue may be research papers (theoretical and experimental), reviews, or analyses of case studies.

Prof. Marco Fossa
Prof. Antonella Priarone
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • heat pumps
  • heat exchangers
  • condensers and evaporators
  • refrigerants
  • heat pump control
  • renewable energy
  • ground source heat pumps
  • energy and buildings

Published Papers (8 papers)

Order results
Result details
Select all
Export citation of selected articles as:

Research

27 pages, 1513 KiB  
Article
An Enhanced Vertical Ground Heat Exchanger Model for Whole-Building Energy Simulation
Energies 2020, 13(16), 4058; https://doi.org/10.3390/en13164058 - 05 Aug 2020
Cited by 7 | Viewed by 2397
Abstract
This paper presents an enhanced vertical ground heat exchanger (GHE) model for whole-building energy simulation (WBES). WBES programs generally have computational constraints that affect the development and implementation of component simulation sub-models. WBES programs require models that execute quickly and efficiently due to [...] Read more.
This paper presents an enhanced vertical ground heat exchanger (GHE) model for whole-building energy simulation (WBES). WBES programs generally have computational constraints that affect the development and implementation of component simulation sub-models. WBES programs require models that execute quickly and efficiently due to how the programs are utilized by design engineers. WBES programs also require models to be formulated so their performance can be determined from boundary conditions set by upstream components and environmental conditions. The GHE model developed during this work utilizes an existing response factor model and extends its capabilities to accurately and robustly simulate at timesteps that are shorter than the GHE transit time. This was accomplished by developing a simplified dynamic borehole model and then exercising that model to generate exiting fluid temperature response factors. This approach blends numerical and analytical modeling methods. The existing response factor models are then extended to incorporate the exiting fluid temperature response factor to provide a better estimate of the GHE exiting fluid temperature at short simulation timesteps. Full article
(This article belongs to the Special Issue Design of Heat Exchangers for Heat Pump Applications)
Show Figures

Figure 1

16 pages, 2851 KiB  
Article
Experimental Hydration Temperature Increase in Borehole Heat Exchangers during Thermal Response Tests for Geothermal Heat Pump Design
Energies 2020, 13(13), 3461; https://doi.org/10.3390/en13133461 - 04 Jul 2020
Cited by 6 | Viewed by 2034
Abstract
The correct design of a system of borehole heat exchangers (BHEs) is the primary requirement for attaining high performance with geothermal heat pumps. The design procedure is based on a reliable estimate of ground thermal properties, which can be assessed by a Thermal [...] Read more.
The correct design of a system of borehole heat exchangers (BHEs) is the primary requirement for attaining high performance with geothermal heat pumps. The design procedure is based on a reliable estimate of ground thermal properties, which can be assessed by a Thermal Response Test (TRT). The TRT analysis is usually performed adopting the Infinite Line Source model and is based on a series of assumptions to which the experiment must comply, including stable initial ground temperatures and a constant heat transfer rate during the experiment. The present paper novelty is related to depth distributed temperature measurements in a series of TRT experiments. The approach is based on the use of special submersible sensors able to record their position inside the pipes. The focus is on the early period of BHE installation, when the grout cement filling the BHE is still chemically reacting, thus releasing extra heat. The comprehensive dataset presented here shows how grout hydration can affect the depth profile of the undisturbed ground temperature and how the temperature evolution in time and space can be used for assessing the correct recovery period for starting the TRT experiment and inferring information on grouting defects along the BHE depth. Full article
(This article belongs to the Special Issue Design of Heat Exchangers for Heat Pump Applications)
Show Figures

Figure 1

23 pages, 3421 KiB  
Article
Experimental Verification of an Analytical Mathematical Model of a Round or Oval Tube Two-Row Car Radiator
Energies 2020, 13(13), 3399; https://doi.org/10.3390/en13133399 - 02 Jul 2020
Cited by 10 | Viewed by 2189
Abstract
The paper presents an analytical mathematical model of a car radiator, which takes into account various heat transfer coefficients (HTCs) on each row of pipes. The air-side HTCs in a specific row of pipes in the first and second passes were calculated using [...] Read more.
The paper presents an analytical mathematical model of a car radiator, which takes into account various heat transfer coefficients (HTCs) on each row of pipes. The air-side HTCs in a specific row of pipes in the first and second passes were calculated using equations for the Nusselt number, which were determined by CFD simulation by the ANSYS program (Version 19.1, Ansys Inc., Canonsburg, PA, USA). The liquid flow in the pipes can be laminar, transition, or turbulent. When changing the flow form from laminar to transition and from transition to turbulent, the HTC continuity is maintained. Mathematical models of two radiators were developed, one of which was made of round tubes and the other of oval tubes. The model allows for the calculation of the thermal output of every row of pipes in both passes of the heat exchangers. Small relative differences between the total heat flow transferred in the heat exchanger from hot water to cool air exist for different and uniform HTCs. However, the heat flow rate in the first row is much higher than the heat flow in the second row if the air-side HTCs are different for each row compared to a situation where the HTC is constant throughout the heat exchanger. The thermal capacities of both radiators calculated using the developed mathematical model were compared with the results of experimental studies. The plate-fin and tube heat exchanger (PFTHE) modeling procedure developed in the article does not require the use of empirical correlations to calculate HTCs on both sides of the pipes. The suggested method of calculating plate-fin and tube heat exchangers, taking into account the different air-side HTCs estimated using CFD modelling, may significantly reduce the cost of experimental research for a new design of heat exchangers implemented in manufacturing. Full article
(This article belongs to the Special Issue Design of Heat Exchangers for Heat Pump Applications)
Show Figures

Figure 1

17 pages, 7448 KiB  
Article
Energy Analysis of a Dual-Source Heat Pump Coupled with Phase Change Materials
Energies 2020, 13(11), 2933; https://doi.org/10.3390/en13112933 - 08 Jun 2020
Cited by 11 | Viewed by 2294
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Design of Heat Exchangers for Heat Pump Applications)
Show Figures

Figure 1

15 pages, 2513 KiB  
Article
Operation of a Tube GAHE in Northeastern Poland in Spring and Summer—A Comparison of Real-World Data with Mathematically Modeled Data
Energies 2020, 13(7), 1778; https://doi.org/10.3390/en13071778 - 07 Apr 2020
Cited by 8 | Viewed by 1714
Abstract
The article analyzes a ground-to-air heat exchanger (GAHE) for a mechanical ventilation system in a building. The heat exchanger’s performance was evaluated in northeastern Poland between May and August of 2016, 2017, and 2018. In spring and summer, the GAHE can be theoretically [...] Read more.
The article analyzes a ground-to-air heat exchanger (GAHE) for a mechanical ventilation system in a building. The heat exchanger’s performance was evaluated in northeastern Poland between May and August of 2016, 2017, and 2018. In spring and summer, the GAHE can be theoretically used to precool air for HVAC systems. The aim of the study was to compare the real-world performance of GAHE with its theoretical performance determined based on the distribution of ground temperature and the temperature at the GAHE outlet modeled in compliance with Standard PN-EN 16798-5 1:2017-07. The modeled values differed considerably from real-world data in May and June, but the model demonstrated satisfactory data fit in July and August. In all years, the modeled average monthly air temperature at the GAHE outlet was 8.3 °C below real-world values in May, but the above difference was only 1.1 °C in August. The developed mathematical model is simple and easy to use, and it can be deployed already in the preliminary design stage. It does not require expensive software or expert skills. However, this study revealed that the model has several limitations. The observed discrepancies should be taken into account when modeling the performance of a GAHE. Full article
(This article belongs to the Special Issue Design of Heat Exchangers for Heat Pump Applications)
Show Figures

Figure 1

17 pages, 2956 KiB  
Article
Performance and Exergy Transfer Analysis of Heat Exchangers with Graphene Nanofluids in Seawater Source Marine Heat Pump System
Energies 2020, 13(7), 1762; https://doi.org/10.3390/en13071762 - 07 Apr 2020
Cited by 9 | Viewed by 2461
Abstract
A marine seawater source heat pump is based on the relatively stable temperature of seawater, and uses it as the system’s cold and heat source to provide the ship with the necessary cold and heat energy. This technology is one of the important [...] Read more.
A marine seawater source heat pump is based on the relatively stable temperature of seawater, and uses it as the system’s cold and heat source to provide the ship with the necessary cold and heat energy. This technology is one of the important solutions to reduce ship energy consumption. Therefore, in this paper, the heat exchanger in the CO2 heat pump system with graphene nano-fluid refrigerant is experimentally studied, and the influence of related factors on its heat transfer enhancement performance is analyzed. First, the paper describes the transformation of the heat pump system experimental bench, the preparation of six different mass concentrations (0~1 wt.%) of graphene nanofluid and its thermophysical properties. Secondly, this paper defines graphene nanofluids as beneficiary fluids, the heat exchanger gains cold fluid heat exergy increase, and the consumption of hot fluid heat is heat exergy decrease. Based on the heat transfer efficiency and exergy efficiency of the heat exchanger, an exergy transfer model was established for a seawater source of tube heat exchanger. Finally, the article carried out a test of enhanced heat transfer of heat exchangers with different concentrations of graphene nanofluid refrigerants under simulated seawater constant temperature conditions and analyzed the test results using energy and an exergy transfer model. The results show that the enhanced heat transfer effect brought by the low concentration (0~0.1 wt.%) of graphene nanofluid is greater than the effect of its viscosity on the performance and has a good exergy transfer effectiveness. When the concentration of graphene nanofluid is too high, the resistance caused by the increase in viscosity will exceed the enhanced heat transfer gain brought by the nanofluid, which results in a significant decrease in the exergy transfer effectiveness. Full article
(This article belongs to the Special Issue Design of Heat Exchangers for Heat Pump Applications)
Show Figures

Figure 1

22 pages, 2636 KiB  
Article
Modelling Heat Pumps with Variable EER and COP in EnergyPlus: A Case Study Applied to Ground Source and Heat Recovery Heat Pump Systems
Energies 2020, 13(4), 794; https://doi.org/10.3390/en13040794 - 11 Feb 2020
Cited by 22 | Viewed by 5783
Abstract
Dynamic energy modelling of buildings is a key factor for developing new strategies for energy management and consumption reduction. For this reason, the EnergyPlus software was used to model a near-zero energy building (Smart Energy Buildings, SEB) located in Savona, Italy. In particular, [...] Read more.
Dynamic energy modelling of buildings is a key factor for developing new strategies for energy management and consumption reduction. For this reason, the EnergyPlus software was used to model a near-zero energy building (Smart Energy Buildings, SEB) located in Savona, Italy. In particular, the focus of the present paper concerns the modeling of the ground source water-to-water heat pump (WHP) and the air-to-air heat pump (AHP) installed in the SEB building. To model the WHP in EnergyPlus, the Curve Fit Method was selected. Starting from manufacturer data, this model allows to estimate the COP of the HP for different temperature working conditions. The procedure was extended to the AHP. This unit is a part of the air-handling unit and it is working as a heat recovery system. The results obtained show that the HP performance in EnergyPlus can closely follow manufacturer data if proper input recasting is performed for EnergyPlus simulations. The present paper clarifies a long series of missed information on EnergyPlus reference sources and allows the huge amount of EnergyPlus users to properly and consciously run simulations, especially when unconventional heat pumps are present. Full article
(This article belongs to the Special Issue Design of Heat Exchangers for Heat Pump Applications)
Show Figures

Figure 1

19 pages, 20516 KiB  
Article
Evaluation of Heat Transfer Performance of a Multi-Disc Sorption Bed Dedicated for Adsorption Cooling Technology
Energies 2019, 12(24), 4660; https://doi.org/10.3390/en12244660 - 08 Dec 2019
Cited by 29 | Viewed by 3128
Abstract
The possibility of implementing the innovative multi-disc sorption bed combined with the heat exchanger into the adsorption cooling technology is investigated experimentally and numerically in the paper. The developed in-house sorption model incorporated into the commercial computational fluid dynamics (CFD) code was applied [...] Read more.
The possibility of implementing the innovative multi-disc sorption bed combined with the heat exchanger into the adsorption cooling technology is investigated experimentally and numerically in the paper. The developed in-house sorption model incorporated into the commercial computational fluid dynamics (CFD) code was applied within the analysis. The research allowed to define the design parameters of the proposed type of the sorption bed and correlate them with basic factors influencing the performance of the sorption bed and its dimensions. The designed multi-disc sorption bed is characterized by great scalability and allows to significantly expand the potential installation sites of the adsorption chillers. Full article
(This article belongs to the Special Issue Design of Heat Exchangers for Heat Pump Applications)
Show Figures

Graphical abstract

Back to TopTop