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36 pages, 23686 KiB

Open AccessFeature PaperArticle

An Assessment of Long-Term Climate Change on Building Energy in Indonesia

by Sheikh Khaleduzzaman Shah, Peter Graham, Craig Burton and Philip Harrington

Energies 2023, 16(21), 7231; https://doi.org/10.3390/en16217231 - 24 Oct 2023

Viewed by 1342

Abstract

This paper reports on modelling outcomes for improvements to building energy performance in Indonesia. Long-term climate effects due to building energy demand and carbon emissions are also considered. The global change assessment model (GCAM) was used to generate the related end-user building energy [...] Read more.

This paper reports on modelling outcomes for improvements to building energy performance in Indonesia. Long-term climate effects due to building energy demand and carbon emissions are also considered. The global change assessment model (GCAM) was used to generate the related end-user building energy data, including socioeconomics, for urban areas of Indonesia. As a comprehensive study, the total life cycle of carbon in the building sector and the concept of zero-carbon buildings, including energy efficiency, zero-emissions electricity and fuel-switching options, were considered. Building shell conductance (U-value) of the building envelope, floor area ratio (FAR), air conditioner (AC) efficiency, electrical appliance (APL) efficiency, rooftop photovoltaic (PV) performance and ground source heat pump (GSHP) systems were considered as parameters to mitigate carbon emissions under the operational energy category in the GCAM. Carbon mitigation associated with the cement production process was considered in the raw material category. Urban population and labour productivity in Indonesia were used as base inputs with projected growth rates to 2050 determined from the available literature. Low growth rate ‘LowRate’ and high growth rate ‘HighRate’ were considered as variable inputs for U-value, FAR, AC efficiency, APLs efficiency and PV capacity factor to model emissions mitigation. The energy consumption of the GSHP was compared to the conventional reverse cycle ACs to identify the potential of the GSHP as a fuel-switching option. In the GCAM, the benchmark (base case scenario) data set was generated based on input parameters (urban population and labour productivity rate) only for the residential building sector in Indonesia. Total potential carbon emissions mitigation was found to be 432 Mt CO₂-e for the residential building sector in Indonesia over 2020–2050. It was found that an average of 24% carbon emissions mitigation could be achieved by 2020–2030 and 76% by 2031–2050. Full article

(This article belongs to the Special Issue Energy Saving Technology in Building)

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19 pages, 5744 KiB

Open AccessArticle

Experimental Study on Spray Cooling Heat Transfer of LN2 for a Large Area

by Jinhong Zhao, Yanming Guo, Qing Ai, Jiaming Gong and Yong Shuai

Energies 2023, 16(9), 3877; https://doi.org/10.3390/en16093877 - 3 May 2023

Cited by 2 | Viewed by 1703

Abstract

Spray cooling has been considered one of the most promising thermal control methods of high-heat flux devices. Most of the spray cooling research focuses on electronic components as the main application object to achieve higher heat dissipation heat flow in ambient temperature regions [...] Read more.

Spray cooling has been considered one of the most promising thermal control methods of high-heat flux devices. Most of the spray cooling research focuses on electronic components as the main application object to achieve higher heat dissipation heat flow in ambient temperature regions for small areas. Water is the most common cooling medium. This paper investigates the application of spray cooling thermal control over large areas. In this study, the heat-transfer characteristics of liquid nitrogen (LN2) for large areas was investigated by conducting experiments. The test surface is 500 mm × 500 mm, which was cooled by a nine-nozzle array. The spray nozzles used in the experiment were conical nozzles with an orifice diameter of 1.6 mm, a spray angle of 120°, and a spray height of 42 mm. Liquid nitrogen was forcefully ejected from nozzles by the high pressure of a liquid storage tank to cool the test surface. According to the cooled surfaces, spray directions, and spray pressures, three groups of experiments were conducted. The results showed that the smooth flat surface has the best heat-transfer performance in three kinds of surface structures, which are macro surface, porous surface, and smooth flat surface. The heat-transfer coefficient varied by ±20% with different spray directions, and the surface heat-transfer coefficient increased linearly with increasing spray pressure. Most of the spray cooling research focuses on heat dissipation in the ambient temperature region for equipment over small areas. The results can benefit thermal control application in various fields. The research in this paper can provide a reference for the application of large-area spray cooling, and the application areas mainly include metal manufacturing processing cooling, aircraft skin infrared radiation characteristics modulation, and laser weapon equipment cooling. Full article

(This article belongs to the Special Issue Energy Saving Technology in Building)

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14 pages, 1838 KiB

Open AccessArticle

Windows of Opportunities: Orientation, Sizing and PV-Shading of the Glazed Area to Reduce Cooling Energy Demand in Sub-Sahara Africa

by Alan Kabanshi, Gasper Choonya, Arman Ameen, Wei Liu and Enock Mulenga

Energies 2023, 16(9), 3834; https://doi.org/10.3390/en16093834 - 29 Apr 2023

Cited by 1 | Viewed by 1573

Abstract

In hot climates, such as sub-Sahara Africa, window sizing and orientation pose challenges as they add, through solar insolation, to the building cooling energy demand and thus the cause of indoor overheating risk. This risk can be reduced through passive building-design-integrated measures, e.g., [...] Read more.

In hot climates, such as sub-Sahara Africa, window sizing and orientation pose challenges as they add, through solar insolation, to the building cooling energy demand and thus the cause of indoor overheating risk. This risk can be reduced through passive building-design-integrated measures, e.g., optimizing the window size, orientation and solar shading strategies. Through an IDA-ICE building performance simulation tool, the current study explores the impact of window size, optimization and building-integrated PV panels as shading strategies on cooling energy demands in three cities (Niamey, Nairobi and Harare) in sub-Sahara Africa. Results show that thermal comfort and cooling energy demand are sensitive to a window-to-wall ratio (WWR) > 70%, while the need for artificial lighting is negligible for a WWR > 50%, particularly in the north for cities in the Southern hemisphere and the south in the Northern hemisphere. A WWR > 70% in the east and west should be avoided unless shading devices are incorporated. Internal blinds perform better in improving occupant thermal comfort but increase artificial lighting while integrating PV panels, as external shading overhangs reduce cooling energy but also produce energy that can be utilized for building services, such as air conditioning. In this study, the results and implications of the optimization of window size, orientation and building-integrated shading and operation are discussed. Full article

(This article belongs to the Special Issue Energy Saving Technology in Building)

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26 pages, 5541 KiB

Open AccessArticle

Will NILM Technology Replace Multi-Meter Telemetry Systems for Monitoring Electricity Consumption?

by Bartłomiej Gawin, Robert Małkowski and Robert Rink

Energies 2023, 16(5), 2275; https://doi.org/10.3390/en16052275 - 27 Feb 2023

Cited by 3 | Viewed by 4039

Abstract

The estimation of electric power utilization, its baseload, and its heating, light, ventilation, and air-conditioning (HVAC) power component, which represents a very large portion of electricity usage in commercial facilities, are important for energy consumption controls and planning. Non-intrusive load monitoring (NILM) is [...] Read more.

The estimation of electric power utilization, its baseload, and its heating, light, ventilation, and air-conditioning (HVAC) power component, which represents a very large portion of electricity usage in commercial facilities, are important for energy consumption controls and planning. Non-intrusive load monitoring (NILM) is the analytical method used to monitor the energy and disaggregate total electrical usage into appliance-related signals as an alternative to installing multiple electricity meters in the building. However, despite considerable progress, there are a limited number of tools dedicated to the problem of reliable and complete energy disaggregation. This paper presents an experiment consisting in designing an electrical system with electrical energy receivers, and then starting NILM disaggregation using machine learning algorithms (MLA). The quality of this disaggregation was assessed using dedicated indicators. Subsequently, the quality of these MLA was also verified using the available BLUED data source. The results show that the proposed method guarantees non-intrusive load disaggregation but still requires further research and testing. Measurement data have been published as open research data and listed in the literature section repository. Full article

(This article belongs to the Special Issue Energy Saving Technology in Building)

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18 pages, 4121 KiB

Open AccessArticle

Experimental Investigation on Heat Transfer Characteristics of Liquid Nitrogen Spray Cooling for Large Area

by Yu Gong, Jinhong Zhao, Wei Li, Qing Ai, Jiaming Gong, Yong Shuai and Chuang Sun

Energies 2023, 16(1), 403; https://doi.org/10.3390/en16010403 - 29 Dec 2022

Cited by 3 | Viewed by 1847

Abstract

Spray cooling has demonstrated advantages in the thermal control of avionic devices. In this study, a spray cooling system is established using liquid nitrogen (LN2) as a working fluid to investigate the effect of heat transfer characteristics on a large heating surface. The [...] Read more.

Spray cooling has demonstrated advantages in the thermal control of avionic devices. In this study, a spray cooling system is established using liquid nitrogen (LN2) as a working fluid to investigate the effect of heat transfer characteristics on a large heating surface. The temperature response measurement and experimental analysis of the heating surface of a large-area shell structure under the boundary conditions of different heat flux and temperature regions were carried out. The temperature response curves for the outer surface of the shell structure from the initial temperature to the set temperature were obtained under different heat flows and temperature zones. The results show that the thermal response time of the surface spray phase cooling is less than 2 s, the stability time for the cooling temperature of the covering layer is longer than 60 s, and the cooling state can be maintained for 30 min under different working conditions. This study can provide a technical reference for the application of spray systems in the field of aircraft cooling. Full article

(This article belongs to the Special Issue Energy Saving Technology in Building)

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15 pages, 2218 KiB

Open AccessArticle

Experimental Investigation on the Vector Characteristics of Concentrated Solar Radiation Flux Map

by Guilong Dai, Ying Zhuang, Xiaoyu Wang, Xue Chen, Chuang Sun and Shenghua Du

Energies 2023, 16(1), 136; https://doi.org/10.3390/en16010136 - 23 Dec 2022

Viewed by 1848

Abstract

It is difficult to measure the concentrated solar radiation flux (CSRF) inside a cavity receiver directly due to the complex geometry of cavity receivers. At present, most reports measure the CSRF at the aperture plane (generally coinciding with the focal plane of solar [...] Read more.

It is difficult to measure the concentrated solar radiation flux (CSRF) inside a cavity receiver directly due to the complex geometry of cavity receivers. At present, most reports measure the CSRF at the aperture plane (generally coinciding with the focal plane of solar concentrators) of the cavity receiver instead of at the absorber wall, which would result in serious aberration because of the obvious difference in configuration between the aperture plane and the absorber wall. To obtain the CSRF at the absorber wall with complex geometry, the vector characteristics (consisting of both directional distributions and spatial distributions) of the CSRF at the focal plane were measured using developed double water-cooled Lambertian targets together with a CCD (charge-coupled device) camera. Then the CSRF images at the absorber wall of a hemisphere cavity receiver were carried out by applying MCRTM (Monte Carlo ray-tracing method) in combination with the measured vector results of the CSRF at the aperture plane. Results show that the directional distributions of the CSRF at the aperture plane are rather nonhomogeneous along the zenith angle and the circumferential angle. The directional distribution performance of the CSRF at the focal plane plays an equally important role in the CSRF images of the cavity receivers. In addition, the relative error of the peak CSRF value of the cavity receiver between the uniform and the measured directional distribution cases is up to 16%. The conclusions provide an important reference for the development of the CSRF measurement. Full article

(This article belongs to the Special Issue Energy Saving Technology in Building)

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18 pages, 3514 KiB

Open AccessArticle

A Numerical Study on Heat Transfer Characteristics of a Novel Rectangular Grooved Microchannel with Al₂O₃/Water Nanofluids

by Xiaoxin Zeng, Hao Yu, Tianbiao He and Ning Mao

Energies 2022, 15(19), 7187; https://doi.org/10.3390/en15197187 - 29 Sep 2022

Cited by 8 | Viewed by 2039

Abstract

The microchannel heat exchanger is one of the most compact and effective heat exchangers used for cooling devices in building air conditioning system, while application of nanofluids in microchannel further enhance its thermal performance due to its much higher thermal conductivity. Considering the [...] Read more.

The microchannel heat exchanger is one of the most compact and effective heat exchangers used for cooling devices in building air conditioning system, while application of nanofluids in microchannel further enhance its thermal performance due to its much higher thermal conductivity. Considering the continuous rapid increase in energy consumption in the building sector, especially in air conditioning systems, the heat transfer performance of a microchannel with nanofluids should be further enhanced to realize energy savings. This study analyzes the influence of combining nanofluid and flow disturbance structure on the heat transfer enhancement of a microchannel, which is also the noted novelty. A rectangular grooved microchannel (RGMC) is proposed, and its thermal performance using Al₂O₃/water nanofluids is investigated using the CFD method, with the mixture model to simulate the Al₂O₃/water nanofluids considering the slip velocity between the base fluid and nanoparticles. The results show that at 1.5 m/s, Nu of RGMC with 2 vol% nanofluids is 38.5% larger than that of smooth microchannel (SMC) with the same nanofluids, and 36.7% larger than that of RGMC with pure water, indicating the much better heat transfer performance of the novel designed RGMC structure. The maximum temperature for RGMC is 5 K lower than SMC with 2 vol% Al₂O₃/water nanofluid at inlet velocity of 1.5 m/s. Further analysis on the integrated effect between fluid flow and heat transfer shows that the synergy angle β near the center line of RGMC is much lower than that of SMC, representing that the better thermal performance is caused by the flow structured induced by the grooves. Moreover, at 1.5 m/s, β_α of SMC with 2 vol% nanofluid is 89.4 Deg, which is 1.66 Deg higher than the β_α value of RGMC, while at 0.25 m/s, the β_α of two types of microchannel are close to each other. This indicates that the groove structure shows greater enhancement at higher inlet velocity. It is concluded that combining nanofluid and groove structure can significantly enhance heat transfer of the microchannel. The nanofluid enhances heat transfer at lower inlet velocity, while the groove structure enhances it at higher inlet velocity. This study will be helpful for the design of a high-efficiency microchannel heat exchanger that promotes building energy savings. Full article

(This article belongs to the Special Issue Energy Saving Technology in Building)

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Review

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45 pages, 11955 KiB

Open AccessReview

A Critical Review on Geometric Improvements for Heat Transfer Augmentation of Microchannels

by Hao Yu, Tongling Li, Xiaoxin Zeng, Tianbiao He and Ning Mao

Energies 2022, 15(24), 9474; https://doi.org/10.3390/en15249474 - 14 Dec 2022

Cited by 13 | Viewed by 3141

Abstract

With the application of microdevices in the building engineering, aerospace industry, electronic devices, nuclear energy, and so on, the dissipation of high heat flux has become an urgent problem to be solved. Microchannel heat sinks have become an effective means of thermal management [...] Read more.

With the application of microdevices in the building engineering, aerospace industry, electronic devices, nuclear energy, and so on, the dissipation of high heat flux has become an urgent problem to be solved. Microchannel heat sinks have become an effective means of thermal management for microdevices and enhancements for equipment due to their higher heat transfer and small scale. However, because of the increasing requirements of microdevices for thermal load and temperature control and energy savings, high efficiency heat exchangers, especially microchannels are receiving more and more attention. To further improve the performance of microchannels, optimizing the channel geometry has become a very important passive technology to effectively enhance the heat transfer of the microchannel heat sink. Therefore, in this paper, the microchannel geometry characteristics of previous studies are reviewed, classified and summarized. The review is mainly focused on microchannel geometry features and structural design to strengthen the effect of heat transfer and pressure drop. In addition, the correlation between boiling heat transfer and geometric characteristics of microchannel flow is also presented, and the future research direction of microchannel geometry design is discussed. Full article

(This article belongs to the Special Issue Energy Saving Technology in Building)

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