Research

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26 pages, 3924 KiB

Open AccessArticle

Towards Sustainable Cities: A Review of Zero Energy Buildings Techniques and Global Activities in Residential Buildings

by Gamal Ali Mohammed, Mahmoud Mabrouk, Guoqing He and Karim I. Abdrabo

Energies 2023, 16(9), 3775; https://0-doi-org.brum.beds.ac.uk/10.3390/en16093775 - 28 Apr 2023

Cited by 2 | Viewed by 2027

Under rapid urbanization-induced global warming and resource depletion, growing interest in zero-energy building (ZEB) and zero-emission building (ZEB) technologies have emerged globally to improve energy performance in homes and shape sustainable cities. Although several countries have released ZEB-enhanced strategies and set national standards [...] Read more.

Under rapid urbanization-induced global warming and resource depletion, growing interest in zero-energy building (ZEB) and zero-emission building (ZEB) technologies have emerged globally to improve energy performance in homes and shape sustainable cities. Although several countries have released ZEB-enhanced strategies and set national standards and policies to promote ZEBs, construction projects are still limited to demonstration projects. This paper reviews global ZEB activities and state-of-the-art technologies for energy-efficient residential building technologies [based on an evaluation of 40 residential buildings]. Over 40 residential buildings on different continents were reviewed, and their technical details and performance were evaluated. Our results show that 62.5% of the buildings achieved the +ZEB standard, 25% of the buildings were net-zero energy buildings, and only 12.5% of the buildings were near-zero energy buildings. Solar PV is the most widely used renewable energy source in the studied cases, while in warmer climates, advanced cooling technologies and heat pumps are the preferred technologies. A building envelope and thermal ventilation with heat recovery are essential in cold climates. Our systematic analysis reveals that the thermal performance of the building envelope and solar energy are the most effective mechanisms for achieving energy efficiency and shaping sustainable cities. Full article

(This article belongs to the Special Issue Latest Research of Building Heat and Mass Transfer)

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18 pages, 4389 KiB

Open AccessFeature PaperArticle

Advanced Method of Variable Refrigerant Flow (VRF) System Design to Forecast on Site Operation—Part 3: Optimal Solutions to Minimize Sizes

by Mykola Radchenko, Andrii Radchenko, Eugeniy Trushliakov, Anatoliy Pavlenko and Roman Radchenko

Energies 2023, 16(5), 2417; https://0-doi-org.brum.beds.ac.uk/10.3390/en16052417 - 03 Mar 2023

Cited by 5 | Viewed by 1274

Abstract

Outdoor air conditioning systems (ACS) are used as autonomic systems as well as in combined outdoor and indoor ACS of the variable refrigerant flow (VRF) type, with variable speed compressors (VSC) as their advanced version. Methods for determining the optimal value of refrigeration [...] Read more.

Outdoor air conditioning systems (ACS) are used as autonomic systems as well as in combined outdoor and indoor ACS of the variable refrigerant flow (VRF) type, with variable speed compressors (VSC) as their advanced version. Methods for determining the optimal value of refrigeration capacity and providing the maximum rate of the summarized annual refrigeration energy generation increment, according to its needs at minimum compressor sizes and rational values, are applied to reveal the reserves for reducing the designed (installed) refrigeration capacity, thus enabling us to practically achieve maximum annual refrigeration energy generation as the primary criterion at the second stage of the general design methodology previously developed by the authors. The principle of sharing the total thermal load on the ACS between the ranges of changeable loads for outdoor air precooling, and a relatively stable load range for further processing air are used as its basis. According to this principle, the changeable thermal load range is chosen as the object for energy saving by recuperating the excessive refrigeration generated at lowered loading in order to compensate for the increased loads, thereby matching actual duties at a reduced designed refrigeration capacity. The method allows us to determine the corresponding level of regulated loads (LRL) of SRC and the load range of compressor operation to minimize sizes. Full article

(This article belongs to the Special Issue Latest Research of Building Heat and Mass Transfer)

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17 pages, 4260 KiB

Open AccessArticle

Advanced Method of Variable Refrigerant Flow (VRF) Systems Designing to Forecast Onsite Operation—Part 2: Phenomenological Simulation to Recoup Refrigeration Energy

by Mykola Radchenko, Andrii Radchenko, Eugeniy Trushliakov, Hanna Koshlak and Roman Radchenko

Energies 2023, 16(4), 1922; https://0-doi-org.brum.beds.ac.uk/10.3390/en16041922 - 15 Feb 2023

Cited by 5 | Viewed by 941

Abstract

This paper focuses on the application of speed-regulated compressors (SRCs) to cover changeable heat loads with high efficiency in conventional air conditioning systems (ACS) as well as in the more advanced variable refrigerant flow (VRF)-type outdoor and indoor ACS. In reality, an SRC [...] Read more.

This paper focuses on the application of speed-regulated compressors (SRCs) to cover changeable heat loads with high efficiency in conventional air conditioning systems (ACS) as well as in the more advanced variable refrigerant flow (VRF)-type outdoor and indoor ACS. In reality, an SRC is an oversized compressor, although it can operate efficiently at part loads. The higher the level of regulated loads (LRL) of the SRC, the more the compressor is oversized. It is preferable to reduce the size of the SRC by covering the peak loads and recouping the excessive refrigeration energy reserved at decreased actual loads within the range of regulated loads. Therefore, the range of changeable loads is chosen as the object to be narrowed by using the reserved refrigeration capacity. Thus, the general fundamental approach of dividing the overall heat load range of the ACS into the ranges with changeable and unchangeable loads, as previously developed by the authors, is applied for the range of primary changeable loads. Due to this innovative step, the principle of two-stage outdoor air conditioning according to changeable and unchangeable loads, also proposed by the authors, has been extended over the range of primary changeable loads to reduce the level of refrigeration capacity regulation and SRC size. To realize this, part of the changeable load range is offset by the reserved refrigeration capacity, leading to a reduction in the changeable load range and the SRC size by approximately 20% for temperate climatic conditions. Full article

(This article belongs to the Special Issue Latest Research of Building Heat and Mass Transfer)

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18 pages, 4521 KiB

Open AccessArticle

Advanced Method of Variable Refrigerant Flow (VRF) Systems Designing to Forecast On-Site Operation—Part 1: General Approaches and Criteria

by Mykola Radchenko, Andrii Radchenko, Eugeniy Trushliakov, Anatoliy Pavlenko and Roman Radchenko

Energies 2023, 16(3), 1381; https://0-doi-org.brum.beds.ac.uk/10.3390/en16031381 - 30 Jan 2023

Cited by 6 | Viewed by 1550

Abstract

All the energetic management and controlling strategies in ambient air conditioning systems (ACS) are aimed to match design load to current needs. This might be achieved by determining a rational value of design thermal load without overestimation that can minimize its deviation from [...] Read more.

All the energetic management and controlling strategies in ambient air conditioning systems (ACS) are aimed to match design load to current needs. This might be achieved by determining a rational value of design thermal load without overestimation that can minimize its deviation from the actual values. The application of variable refrigerant flow (VRF) systems with speed-regulated compressors (SRC) is considered as the most advanced trend in building air conditioning due to the ability of SRCs to cover changeable heat loads without lowering their efficiency. The level of load regulation by SRC is evaluated as the ratio of the load range, regulated by SCR, to the overall design load range. With this, the range of actual changeable loads is usually supposed to be covered by SRC entirely while keeping the rest, unregulated, and load range unchangeable. However, to confirm this, the rest load range behind the regulated one should be investigated to estimate the efficiency of SRC operation. Therefore, the approach to dividing the overall thermal load range of ambient air conditioning into the ranges of changeable and unchangeable loads to compare with those covered by SRC is used. From this approach, the method of rational designing and shearing a design refrigeration capacity in response to current loading, based on the principle of two-stage ambient air conditioning, has been widened on the VRF systems to estimate the efficiency of SCR application. This was realized by imposing the load ranges regulated by SRC onto the ranges of changeable and unchangeable loads within the overall range of actual loading. The proposed innovative criteria and indicators for rational shearing the load ranges to match current duties and load level evaluation can reveal the reserves for improving the efficiency of SRC compressor operation and the ACS of VRF type as a whole. Full article

(This article belongs to the Special Issue Latest Research of Building Heat and Mass Transfer)

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18 pages, 5958 KiB

Open AccessArticle

Enhancing the Efficiency of Integrated Energy Systems by the Redistribution of Heat Based on Monitoring Data

by Andrii Radchenko, Mykola Radchenko, Hanna Koshlak, Roman Radchenko and Serhiy Forduy

Energies 2022, 15(22), 8774; https://0-doi-org.brum.beds.ac.uk/10.3390/en15228774 - 21 Nov 2022

Cited by 9 | Viewed by 1332

Abstract

Integrated energy systems (IES) for combined power, heat and refrigeration supply achieved a wide application due to high flexibility in matching current loading. So as electricity is easily convertible into any other form of energy, gas engines are widely applied as driving engines [...] Read more.

Integrated energy systems (IES) for combined power, heat and refrigeration supply achieved a wide application due to high flexibility in matching current loading. So as electricity is easily convertible into any other form of energy, gas engines are widely applied as driving engines characterized by high electrical and overall efficiency of about 45% and 90%, respectively. However, the highest thermal efficiency is achieved at full matching heat generated by the engine and heat transformed. This is often impossible in actual practice, especially if the heat is transformed into refrigeration by the most efficient and widespread absorption lithium-bromide chillers (ACh) and the heat not consumed by the ACh is removed from the atmosphere through an emergency radiator. The unused heat might be transformed by an ejector chiller (ECh) as the simplest and cheapest. So as the thermodynamic efficiency of any combustion engine is influenced essentially by the sucked air temperature, the excessive refrigeration produced by the ECh, is used for IES cooling to generate additional electricity and increase the electrical and overall efficiency of the engine. Such a redistribution of heat enables the enhancement of the efficiency of IES with an absorption-ejector chiller (AECh). The modified criteria for the comparative estimation of thermodynamic efficiency of innovative IESs with AEChs without overgenerated heat lost against a typical IES with an ACh and heat lost are proposed. In contrast to well-known electrical and heat efficiency, it considers the magnitude of heat loss and enables us to compare the heat efficiency of any version of transforming heat to refrigeration with an ideal basic version of IES based on a highly efficient ACh, transforming all the heat removed from the engine without heat loss. Some alternative scheme decisions for heat recovery systems have been developed based on monitoring data. They might be easily implemented into a typical IES with ACh. Full article

(This article belongs to the Special Issue Latest Research of Building Heat and Mass Transfer)

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22 pages, 3916 KiB

Open AccessArticle

Polymer Membranes for Enthalpy Exchangers

by Kamil Križo, Andrej Kapjor and Michal Holubčík

Energies 2022, 15(16), 6021; https://0-doi-org.brum.beds.ac.uk/10.3390/en15166021 - 19 Aug 2022

Cited by 3 | Viewed by 982

Abstract

A membrane-based enthalpy exchanger is a device used for heat and humidity recovery in ventilated buildings. The energy-saving potential of such a device is dependent on the parameters responsible for heat and moisture recovery. The trend is toward composite membranes, which are custom [...] Read more.

A membrane-based enthalpy exchanger is a device used for heat and humidity recovery in ventilated buildings. The energy-saving potential of such a device is dependent on the parameters responsible for heat and moisture recovery. The trend is toward composite membranes, which are custom produced, and their parameters can be adjusted for a given application; therefore, the diffusion and sorption characteristics of such membranes are unknown. In order to obtain the values of the water vapor diffusivity of three investigated handmade membranes, a serial resistance model using a Field and Laboratory Emission Cell (FLEC) is proposed. Experiments were conducted to identify the resistance in each step of the moisture transfer process to extract the moisture diffusivity in the membranes. The calculated moisture diffusivities in the membranes were 8.99 × 10⁻¹² (m²/s) for the membranes from cellulose acetate, 1.9 × 10⁻¹⁰ (m²/s) for the microporous PE/PUR membranes, and 1.53 × 10⁻¹¹ (m²/s) for the PET/PUR microfibrous membranes. The obtained membrane diffusivities were then used in the proposed effectiveness-NTU-based model of an exchanger with a cross-flow arrangement to predict performance under various operating conditions. The results show that the highest latent effectiveness was found for the exchanger core made from the PE/PUR membrane and the lowest was for the one with the PE/PUR membrane core. Full article

(This article belongs to the Special Issue Latest Research of Building Heat and Mass Transfer)

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16 pages, 6029 KiB

Open AccessArticle

Evaluation of Heat Transfer Rates through Transparent Dividing Structures

by Borys Basok, Borys Davydenko, Volodymyr Novikov, Anatoliy M. Pavlenko, Maryna Novitska, Karolina Sadko and Svitlana Goncharuk

Energies 2022, 15(13), 4910; https://0-doi-org.brum.beds.ac.uk/10.3390/en15134910 - 05 Jul 2022

Cited by 6 | Viewed by 1855

Abstract

In this paper, heat transfer and airflow in the gap between the panes of a central part of a double-glazed window were investigated using mathematical modeling. It has been shown that the cyclical airflow regime, in the form of ascending and descending boundary [...] Read more.

In this paper, heat transfer and airflow in the gap between the panes of a central part of a double-glazed window were investigated using mathematical modeling. It has been shown that the cyclical airflow regime, in the form of ascending and descending boundary layers, loses stability and changes to a vortex regime under certain conditions depending on the gap width, transverse temperature gradient, inclination angle and window height, as in Rayleigh–Bernard convection cells. The study made it possible to determine the critical values of the Rayleigh number (Ra) at which the air flow regime in the gap between the panes of a window changes (in the range of values 6.07 × 10³ < Ra < 6.7 × 10³). As a result of the modeling, the values of the thermal resistance of a central part of double-glazed window were determined as a function of the width of the gap between the panes, the angle of inclination and the transverse temperature gradient. Full article

(This article belongs to the Special Issue Latest Research of Building Heat and Mass Transfer)

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Review

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23 pages, 4889 KiB

Open AccessReview

Evaluation of Numerical Methods for Predicting the Energy Performance of Windows

by Anatoliy M. Pavlenko and Karolina Sadko

Energies 2023, 16(3), 1425; https://0-doi-org.brum.beds.ac.uk/10.3390/en16031425 - 01 Feb 2023

Cited by 6 | Viewed by 1571

Abstract

Windows are important structural components that determine the energy efficiency of buildings. A significant parameter in windows technology is the overall heat transfer coefficient, U. This paper analyzes the methods of numerical determination of the U-value, including for windows that use passive technologies [...] Read more.

Windows are important structural components that determine the energy efficiency of buildings. A significant parameter in windows technology is the overall heat transfer coefficient, U. This paper analyzes the methods of numerical determination of the U-value, including for windows that use passive technologies to improve thermal performance. The analysis was intended to evaluate the heat flux and temperature distribution across glazed surfaces and the accuracy of traditional approaches to the determination of heat loss through window structures. The results were obtained using the heat flux measurement method described in the international standard ISO 9869-1:2014. The paper shows that the non-uniformity of the heat flux density on a window surface can be as high as 60%, which in turn generates an error in the calculations based on stationary heat transfer conditions. Full article

(This article belongs to the Special Issue Latest Research of Building Heat and Mass Transfer)

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