Submit to Energies Review for Energies Propose a Special Issue

Journal Menu

Journal Browser

► Journal Browser

New Insights into Heat Recovery and Air Conditioning

Print Special Issue Flyer
Special Issue Editors
Special Issue Information
Keywords
Published Papers

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

Deadline for manuscript submissions: closed (30 November 2023) | Viewed by 12543

Share This Special Issue

Special Issue Editors

Dr. Sławomir Rabczak

E-Mail Website
Guest Editor

The Faculty of Civil and Environmental Engineering and Architecture, Rzeszow University of Technology, 35-959 Rzeszow, Poland
Interests: heat recovery; air conditioning; ventilation; renewable heat sources; heat pump; cooling
Special Issues, Collections and Topics in MDPI journals

Prof. Dr. Daniel Słyś

E-Mail Website
Guest Editor

Department of Infrastructure and Water Management, Rzeszow University of Technology, Al. Powstańców Warszawy 6, 35-959 Rzeszów, Poland
Interests: waste heat recovery systems; sewage systems; underground infrastructure; modeling of infrastructure; water management; rainwater harvesting systems; retention
Special Issues, Collections and Topics in MDPI journals

Dr. Krzysztof Nowak

E-Mail Website
Guest Editor

The Faculty of Civil and Environmental Engineering and Architecture, Rzeszow University of Technology, 35-959 Rzeszow, Poland
Interests: renewable energy sources; ventilation; heat pump; heat recovery; biomass; photovoltaic; solar energy; air pollution; co-combustion
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues

We are encouraging submissions to a Special Issue of Energies on "New insights into Heat Recovery and Air Conditioning". Heat recovery is now a necessary component in the design of even simple ventilation and air conditioning systems. In addition, energy-recovery systems are used in refrigeration systems, sewage systems, swimming pool systems and in many technological processes. Energy recovery is a very broad concept prospective authors are encouraged to present their research results, unique technical solutions and scientific concepts in this area. It is difficult to imagine modern solutions in the building, industry, infrastructure and energy sectors without heat recovery, either directly or through systems based on renewable energy sources such as ground, air or/and sun. The multitude of systems that allow one to obtain energy from the above-mentioned sources is very large, from systems such as ground heat exchangers, ground heat pumps, geothermal energy, passive and active heat pump systems and air heat pumps, to solar systems, photovoltaic, regenerative and recuperative exchangers. We are confident that contributors to this Special Issue will find an opportunity to share interesting research results in the proposed fields, which will contribute to an increase in the level of knowledge regarding rational energy management while promoting inclusive solutions. This is very important due to the strong trend of changes that are currently taking place worldwide and the need to optimize the energy of existing solutions or to put forward new proposals aimed at increasing human resilience in the surrounding environment.

The topics of this Special Issue are addressed in the following list of keywords:

Energy recovery;
Renewable energy sources;
Energy accumulation;
Air heat exchangers;
Heat sources;
Passive heat pumps;
Active heat pumps;
Free cooling;
Natural cooling;
Ventilation and air conditioning;
Refrigeration systems;
Solar systems;
Photovoltaic systems;
Heat recovery in sewage systems and networks;
Heat recovery in swimming pool installations;
Heat recovery in industrial installations.

Dr. Sławomir Rabczak
Prof. Dr. Daniel Słyś
Dr. Krzysztof Nowak
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

energy recovery
integrated systems
ventilation and air conditioning
renewable energy sources
waste heat
recuperation and regeneration
heat pumps
refrigeration
natural cooling
solar systems

Published Papers (6 papers)

Download All Papers

Order results

Result details

Show export options Show export options

Select all

Export citation of selected articles as:

Research

22 pages, 3966 KiB

Open AccessArticle

Energy and Exergy Analysis of Vapor Compression Refrigeration System with Low-GWP Refrigerants

by Tauseef Aized, Muhammad Rashid, Fahid Riaz, Ameer Hamza, Hafiz Zahid Nabi, Muhammad Sultan, Waqar Muhammad Ashraf and Jaroslaw Krzywanski

Energies 2022, 15(19), 7246; https://doi.org/10.3390/en15197246 - 02 Oct 2022

Cited by 6 | Viewed by 3470

Abstract

In this paper, a first- and second-law analysis of vapor compression refrigeration is presented to estimate and propose the replacement of R134 with working fluids having less global warming potential (GWP) and less exergy destruction and irreversibilities. Six different refrigerants were studied, namely, R717, R1234yf, R290, R134a, R600a, and R152a. A thermodynamic model was designed on Engineering Equation Solver (EES) software, and performance parameters were calculated. The model was deployed on all six refrigerants, while the used output parameters of performance were cooling capacity, coefficient of performance, discharge temperature, total exergy destruction, relative exergy destruction rates of different components, second-law efficiency, and efficiency defect of each component. The performance parameters were estimated at different speeds of the compressor (1000, 2000, and 3000 rpm) and fixed condenser and evaporator temperatures of 50 °C and 5 °C, respectively. The isentropic efficiency of the compressor was the same as the volumetric efficiency, and it was taken as 75%, 65%, and 55% at the compressor speeds of 1000 rpm, 2000 rpm, and 3000 rpm, respectively. A comparison of the performance parameters was presented by importing the results in MATLAB. It was found that the compressor had the highest exergy destruction compared to the other components. It was found that R152 was the refrigerant with zero ozone depletion potential (ODP) and a GWP value of 140 with less exergy destruction and irreversibilities. Moreover, it was easy to use R152a with good thermodynamic characteristics. It is estimated that R152a is a suitable replacement for R134a, as it can be used with few modifications. Full article

(This article belongs to the Special Issue New Insights into Heat Recovery and Air Conditioning)

► Show Figures

Figure 1

22 pages, 3949 KiB

Open AccessArticle

Horizontal Shower Heat Exchanger as an Effective Domestic Hot Water Heating Alternative

by Sabina Kordana-Obuch and Mariusz Starzec

Energies 2022, 15(13), 4829; https://doi.org/10.3390/en15134829 - 01 Jul 2022

Cited by 10 | Viewed by 1913

Abstract

Wastewater has significant potential as a source of clean energy. This energy can be used both within external sewer networks and on the scale of individual residential buildings, and the use of shower heat exchangers appears to be the most reasonable solution. However, in the case of Poland, the problem is still the unwillingness of society to use this type of solution, caused mainly by the lack of space for the installation of vertical drain water heat recovery (DWHR) units and the low efficiency of horizontal units. In response to this issue, the efficiency of a new compact shower heat exchanger designed to be mounted below the shower tray, as well as its linear counterpart, was investigated under various operating conditions. In addition, the financial efficiency of using the compact DWHR unit with average water consumption for showering was evaluated. For this purpose, discount methods were used to estimate the financial efficiency of investments. The study showed that the compact shower heat exchanger has higher efficiency than its linear counterpart. Depending on the temperature of cold water and the flow rate of both media through the heat exchanger, it achieves efficiencies ranging from 22.43% to 31.82%, while the efficiency of the linear DWHR unit did not exceed 23.03% in the study. The financial analysis showed that its use is particularly beneficial when the building uses an electric hot water heater. The investment’s sensitivity to changes in the independent variables is small in this case, even with low water consumption per shower. The only exceptions are investment outlays. Therefore, the compact DWHR unit is a clean energy device, which in many cases is financially viable. Full article

(This article belongs to the Special Issue New Insights into Heat Recovery and Air Conditioning)

► Show Figures

Figure 1

24 pages, 5100 KiB

Open AccessArticle

Selection of Energy Improvement Factors and Economic Analysis of Standard MDU Complexes in Korean Metropolitan Regions

by Ki-Won Lee and Young Il Kim

Energies 2022, 15(11), 4042; https://doi.org/10.3390/en15114042 - 31 May 2022

Cited by 1 | Viewed by 1247

Abstract

In Korea, energy consumption within apartments in metropolitan areas accounted for more than 33% of the total energy consumption by buildings in 2020. In this study, in order to increase the energy efficiency of MDU (multi-dwelling unit) complexes in metropolitan areas, improvement factors and economic effects were analyzed using ECO2, a building energy efficiency evaluation program. Optimal improvement measures are proposed, to reduce the economic burden on users by applying energy saving technologies. This study was conducted in four stages; in the first stage, using ECO2 software, five types of apartments were selected as standards among 46 complexes. Standard MDUs were selected if more than two factors were satisfied from among the following: (1) household type, (2) average exterior wall insulation and window performance, (3) average energy consumption and demand per unit area per year, (4) average applied facility system, and (5) average monthly energy demand per unit area. In the second stage, improvement factors were derived by analyzing the 10 most recent energy efficient MDU complexes. The third stage involved analysis of the energy saving effect generated by the improvement of windows and total heat exchangers in five selected complexes. Primary energy consumption per unit area per year improved from 158.8 to 132. kWh/m²y in complex E, which had been upgraded from ‘floor heating system’ to ‘total heat exchanger’. Finally, in the fourth stage, optimal improvement factors were selected for economic analysis. By simultaneously applying the optimal improvement factors, such as windows and total heat exchanger, to the M complex, primary energy consumption per unit area per year was improved from 147.6 to 111.4 kWh/m² y. When optimal improvement factors were applied to 59 m², 74 m², 84 m² types in complex M, life cycle cost savings of energy consumption for 30 years became $1384~1970. Full article

(This article belongs to the Special Issue New Insights into Heat Recovery and Air Conditioning)

► Show Figures

Figure 1

18 pages, 6962 KiB

Open AccessArticle

Cooling Performance Enhancement of a 20 RT (70 kW) Two-Evaporator Heat Pump with a Vapor–Liquid Separator

by Won-Suk Yang and Young Il Kim

Energies 2022, 15(11), 3849; https://doi.org/10.3390/en15113849 - 24 May 2022

Viewed by 1558

Abstract

20 RT (70 kW) two-evaporator heat pump system was developed, manufactured, and tested to enhance the cooling performance using a vapor–liquid separator. In the proposed system, two evaporators are connected in series, and the refrigerant passing through the primary evaporator is separated into vapor and liquid using a vapor–liquid separator. The vapor refrigerant is passed to the compressor, whereas the liquid phase flows into the second evaporator. The amount of vapor refrigerant sent to the compressor can be adjusted through a needle valve opening (0%, 50%, and 100%). The influence of this parameter on the cooling performance was analyzed. The cooling performance tests were repeated five times to check repeatability. Data associated with the air and refrigerant sides were obtained, and the average coefficients of performance (COPs) were calculated. The average COP associated with the air side was approximately 5% lower than that pertaining to the refrigerant side owing to the heat loss. In terms of the air-side cooling performance, the average COP was 3.14, 3.40, and 3.68 when the valve openings were 0%, 50%, and 100%, respectively. The cooling performance when the valve opening was 100% was 17.2% higher than that for the valve opening of 0%. The findings demonstrated that the cooling performance of a heat pump can be enhanced using two evaporators and a vapor–liquid separator. Full article

(This article belongs to the Special Issue New Insights into Heat Recovery and Air Conditioning)

► Show Figures

Figure 1

10 pages, 1622 KiB

Open AccessArticle

Possibilities of Adapting a Free-Cooling System in an Existing Commercial Building

by Sławomir Rabczak and Krzysztof Nowak

Energies 2022, 15(9), 3350; https://doi.org/10.3390/en15093350 - 04 May 2022

Cited by 4 | Viewed by 1800

Abstract

Increasingly, the exploitation of buildings involves the need for comprehensive management of all systems operating within it, their continuous monitoring, both for the safety of users and to mainly optimize the operating parameters of systems that are largely dependent on each other, interact with each other. This is mainly associated with the need for the most energy-efficient management of energy consumption, which has the largest share of operating costs. The main cost for the facilities is the cooling aspect, which is significant, and for this reason, it is necessary to analyze the possibility of its minimization. One of the possible systems to consider in order to reduce the consumption of cooling energy in the facility is the application of free-cooling technology, which is based on the use of the natural cooling capacity of the outside air for cooling rooms with high heat gains. The application of the free cooling system for facilities with a relatively stable cooling load, with significant heat gains from equipment is justified due to the possibility of maintaining low room temperatures, below the comfort value for people, for a long period of time. The problem arises when a large proportion of the heat gains are from people. In such a situation, cooling of rooms is possible but requires a large amount of ventilation air, which is already a serious limitation on the one hand because of the existing air conditioning equipment, lack of possibility to increase the ventilation air stream; on the other hand, the low heat capacity of the air itself, compared to, e.g., water systems used for cooling of the facility or multisplit systems. These limitations put a question mark over the possibility of adapting the technology of free cooling for the existing facilities, where the majority of heat gains come from people. It is not possible in such objects to lower the room temperature below the limit values for the sake of thermal comfort, which in itself limits the possibilities of using air as a natural cooling agent in such objects. Based on the measurement data obtained from the object, it was decided to check the possibilities of applying free-cooling technology in a large shopping facility and obtaining an answer as to what extent it is possible to reduce the power of cooling units with the application of free-cooling exchangers. Full article

(This article belongs to the Special Issue New Insights into Heat Recovery and Air Conditioning)

► Show Figures

Figure 1

28 pages, 5813 KiB

Open AccessArticle

Development of CO₂ Concentration Prediction Tool for Improving Office Indoor Air Quality Considering Economic Cost

by Yeo-Kyung Lee, Young Il Kim and Woo-Seok Lee

Energies 2022, 15(9), 3232; https://doi.org/10.3390/en15093232 - 28 Apr 2022

Cited by 5 | Viewed by 1440

Abstract

Ventilation is becoming increasingly important to improve indoor air quality and prevent the spread of COVID-19. This study analyzed the indoor air quality of office spaces, where occupants remain for extended periods, among multi-use facilities with an increasing need for ventilation system application. A “tool for office space CO₂ prediction and indoor air quality improvement recommendation” was developed. The research method was divided into four steps. Step 1: Analysis of indoor air quality characteristics in office spaces was carried out with a questionnaire survey and indoor air quality experiment. Based on the CO₂ concentration, which was found to be a problem in the indoor air quality experiment in the office space, Step 2: CO₂ concentration prediction tool for office spaces, which requires inputs of regional and spatial factors and architectural and equipment elements, was developed. In Step 3: Development and verification of prediction tool considering economic feasibility, the cost of energy recovery ventilation systems based on the invoices of the energy recovery ventilation manufacturers was analyzed. In Step 4: Energy recovery ventilation proposal and indoor CO₂ forecast, Office Space B, which can accommodate up to 15 people, was derived as an example of the proposed tool. As a result of the prediction, the optimal air volume of the energy recovery ventilation was determined according to the “office CO₂ prediction and indoor air quality improvement recommendations”. This study introduced simple tools, which can be used by non-experts, that are capable of showing changes in indoor air quality, CO₂ concentration and cost according to activities. Full article

(This article belongs to the Special Issue New Insights into Heat Recovery and Air Conditioning)

► Show Figures

Journal Menu

Journal Browser

New Insights into Heat Recovery and Air Conditioning

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Published Papers (6 papers)

Research

Further Information

Guidelines

MDPI Initiatives

Follow MDPI