Air Conditioning System Energy Research Articles

Mathematical Analysis of Energy and Exergy loss in Air Conditioning system as Affected by Ambient Temperature

The article provides a Mathematical analysis of exergy in air-conditioning as affected by ambient temperature. The Mathematical simulation model employs an integrated air conditioning system subjected to varying ambient temperatures to monitor the changes in the four primary components: the compressor, condenser, capillary, and evaporator, in relation to ambient temperature. The examination of the exergy of the four devices revealed that the capillary exhibits an anomalous increase in exergy loss with rising ambient temperature, in contrast to the other devices. The findings indicate that minimizing exergy loss in the capillary, affected by ambient temperature, is crucial for enhancing the operational efficiency of an air-conditioning system when accounting for ambient temperature effects. The elevated ambient temperature results in a greater pressure drop in the capillary and increased exergy loss.

The Optimization of Chillers Air-Conditioning in Thailand Supermarkets using a Retail Energy Management System (REMS)

Supermarkets in Thailand continue to grow and there will be more than 1500 branches by 2023 open 18-24 hours a day. In this research, we will present how to increase energy efficiency in retail stores by reducing the energy consumption of compressors of chiller air conditioning systems by using energy management systems in retail stores. Retail energy management systems in retail stores use the Internet of Things to connect to a device to store data and analyze and process from big data, then Artificial Intelligence controls and commands to make the air conditioning system energy efficient. Controlling 10 AHUs using central sensors at the sales area instead of return sensors allows us to save 25% of energy or 12,886 kWh/Year. As for the cold-water pump, it is controlled by an inverter. By using sensors to measure the water flow rate, we save 33% of energy or 19,755 kWh/Year. When controlling the water pump and AHU, the chiller compressor will save energy because when the air handling unit and the water pump have reduced work, the work of the compressor to cool water is reduced as well, resulting in energy savings of 12% or 25,211 kWh/Day. Using such a system reduces the overall energy consumption of the chiller air conditioning system. 17% or 57,852 per year has a payback period of 3 years and can also be extended to other systems within the store or other stores.

Energy and exergy analysis of an experimental NH3-LiNO3 air-conditioning absorption system

An energy and exergy analysis of an experimental air-conditioning absorption system operating with the ammonia-lithium nitrate mixture has been performed. The system was operated under controlled and steady-state conditions. The main operating parameters, such as flow ratio, coefficient of performance, exergy coefficient of performance, and exergy destruction in each one of the main components, were determined at different heat sources and condensing temperatures. The coefficients of performance varied between 0.5 and 0.65, while the exergy coefficients of performance varied between 0.1 and 0.2. Clear trends were found for the coefficient of performance and flow ratio as a function of the generator and condenser temperatures; however, no trends were found in the exergy coefficients of performance due to the high variability of the ambient temperature. The highest values of the exergy destruction occurred in the generator, followed by the condenser and the evaporator, while the lowest values were obtained in the absorber and the economizer.

A comparative evaluation on energy consumption of a building using bio-based and paraffin-based phase change materials integrated to external building envelope

Using thermal energy storage such as phase change materials (PCMs) is a suitable solution to reduce energy consumption in order to maintain thermal comfort conditions inside the building. There is a wide range of phase change materials according to their different characteristics such as melting temperature, freezing temperature, latent heat capacity, specific heat value of solid and liquid phase, thermal conductivity coefficient, and charge and discharge range, which makes it difficult to choose the right PCM. In this research, two common groups of phase change materials that are used commercially are studied and after performing a sensitivity analysis on them, a suitable temperature range is selected. Then the selected PCMs are placed in different parts of the external envelopes of the building and various parameters such as air conditioning system energy consumption, thermal comfort, heat balance, etc. are examined. It should be noted that in this study, the use of PCMs in buildings with cooling and heating systems is investigated. In order to carry out the simulation, a two-story office building located in Arak, Iran was modeled in Design Builder software along with all the details. The outputs show that if Bio PCM is used in the outer layer of the wall in the summer season, it is possible to save up to 154 w/m2 in the energy required for cooling the building. While the use of Bio PCM M91 Q21 material in the inner layer of the wall will reduce the load of the cooling system by 246.15 Wh/m2. Also, if RT PCM is used, it is possible to reduce the heat load by 80%. Furthermore, by analyzing the optimal cases, it can be concluded that increasing the thickness of the PCM layer cannot effectively improve the thermal performance of the building. On the contrary, their reduction in some cases leads to a reduction in energy demand in the building. Finally, in order to generalize the results, the optimal situation was compared with two similar climates of Arak city.

Granularity Optimization for Efficient Energy Consumption Monitoring in Subway Stations for Enhanced Energy Management

Efficient energy data management forms a critical foundation for unlocking the carbon reduction potential of subway systems, holding significant importance in advancing urban processes towards lowcarbon and clean environments. Low-precision sampling is difficult to reflect the actual energy consumption of the station, and high-precision sampling has high requirements for the data storage and transmission capacity of the monitoring system. In order to determine the appropriate sampling accuracy, this study analyses the power load fluctuation characteristics of stations on a subway line in the North China Plain and optimizes the sampling granularity for achieving minimal data storage requirements while effectively capturing energy consumption fluctuation information. The findings indicate that a higher sampling granularity for power load monitoring is advisable during the summer to capture the frequent fluctuation characteristics of ventilation and air-conditioning system energy consumption. For a typical underground station, it is recommended to use a sampling interval of 5 min in summer and 15 min or longer in other seasons. For a typical elevated station, a sampling interval of 10 min is recommended in summer, and 20 min or longer in other seasons.

Real-time energy and economic performance of the multi-zone photovoltaic-drive air conditioning system for an office building in a tropical climate

Real-time energy and economic performance of the multi-zone photovoltaic-drive air conditioning system for an office building in a tropical climate

Optimization of air-conditioning load for a residential building using Taguchi method

Economic growth has been raised in many countries in recent years, prompting people to seek out human comforts. For human comfort, residential buildings consume a significant amount of energy for air-conditioning systems. Building materials are the most significant factor in deciding the air-conditioning load. In this research work, a typical residential flat model is prepared using AutoCAD software and the building energy simulation is done for this model using hourly analysis program software. The results obtained from the building simulation are optimized using the Taguchi method. For optimizing the air-conditioning load, five influencing factors such as the overall heat transfer coefficient of wall (A), thickness of roof insulation material (B), heat transfer coefficient of window glass (C), bypass factor (D) and cooling coil supply temperature (E) of air-conditioning equipment at three levels are selected. For the experimental tests, an orthogonal L27 arrangement is chosen for experimental trials and in every trial, air-conditioning load of the typical residential flat has been calculated. After that, using Minitab 17 statistical software, the signal-to-noise ratios are obtained for different factors by selecting smaller-is-better option. After studying the response table for Taguchi tests, the optimum levels for all five factors are obtained. The analysis of variance method was also used to identify the main factors affecting the results significantly by finding out the contribution of all five factors in percentage. The results indicated that the most efficient set of all five factors is A1B3C1D2E3 and the most affecting factor is the wall material of the residential flat having a contribution of 91.91%.

The Review of the Application of the Heat Pipe on Enhancing Performance of the Air-Conditioning System in Buildings

An air-conditioning system (ACS), which consumes large amounts of high-grade energy, is essential for maintaining the indoor thermal environment of modern buildings. However, an ACS consumes almost half of the total energy of the building. Therefore, it is necessary to reduce the energy consumption of the ACS to promote energy conservation and emission reduction in the building sector. In fact, there is an abundance of waste heat and low-grade energies with the potential to be utilized in ACS in nature, but many of them are not utilized efficiently or cannot be utilized at all due to the low efficiency of thermal energy conversion. Known as a passive thermal transfer device, the application of a heat pipe (HP) in the ACS has shown explosive growth in recent years. HPs have been demonstrated to be an effective method for reducing building cooling and heating demands and energy consumption in ACS with experimental and simulation methods. This paper summarizes the different HP types applied in the ACS and provides brief insight into the performance enhancement of the ACS integrated with HP. Four types of HPs, namely tubular HP (THP), loop HP (LHP), pulsating HP (PHP) and flat HP (FHP), are presented. Their working principles and scope of applications are reviewed. Then, HPs used in natural cooling system, split air conditioner (SAC), centralized ACS (CACS) and cooling terminal devices are comprehensively reviewed. Finally, the heat transfer characteristics and energy savings of the above systems are critically analyzed. The results show that the performance of the HP is greatly affected by its own structure, working fluid and external environmental conditions. The energy saving of ACS coupled with HP is 3–40.9%. The payback period of this system ranges from 1.9–10 years. It demonstrates that the HP plays a significant role in reducing ACS energy consumption and improving indoor thermal comfort.

A hybrid WOA-SVM based on CI for improving the accuracy of shopping mall air conditioning system energy consumption prediction

Energy consumption prediction is of great practical significance for the study of energy-saving scheduling of building air-conditioning systems. However, there are two problems in prediction models: (1) A single prediction model is difficult to solve the nonlinear problem of building energy consumption data. (2) A single prediction result can hardly reflect the uncertainty in the building operation process. Therefore, in this study, a hybrid prediction model with an improved whale optimization algorithm- optimization support vector machine (IWOA-SVM) is proposed based on the air conditioning system of a shopping mall in Xi'an. The WOA is improved using the opposition-based learning strategy (OBL), differential evolution algorithm (DE), and introducing a control parameter λ. The Confidence Interval (CI) of the model fitting error is used to represent the prediction results. The results show that the root mean square error (RMSE) of the optimized model is reduced by 9.5, and the (RMSE) of the total energy consumption prediction value after adding CI is >1.68. The method achieves higher model accuracy, reflecting the operational fluctuations of the building.

Audit energi sistem tata cahaya dan tata udara lantai 2 & 3 pada bangunan gedung toko buku di Pekanbaru

Energy audit is a technique used to analyze the amount of energy consumption in buildings and identify ways or methods to save it. Based on the Minister of Human Resources Regulation No. 13 of 2012 stated rules regarding energy management and energy saving standards. Shopping buildings are one of the sectors that use electrical energy to operate. A bookstore in Pekanbaru which consists of three floors also uses electrical energy for lighting and air conditioning systems. The use of electricity for lighting and air conditioning for a month is 37985.5 kWh and then ECO is carried out so that the use of electrical energy can be reduced to 30,138 kWh in each month. The use of electrical energy can be expressed in Energy Consumption Intensity (IKE), before the ECO IKE was carried out for the 2nd and 3rd floors of the bookstore building in Pekanbaru was 28.59 and after energy saving opportunities, the Energy Consumption Index became 23.09.

Release of Energy from Groundwater/with Reduction in CO2 Emissions of More Than 50% from HVAC in the Extension and Revitalization of the Former Palace of the Sobieski Family in Lublin

The direct release of energy from the groundwater under the building of the Sobieski Family Palace in Lublin, Poland, and the obtainment of heat and cooling energy for Heating, Ventilation, and Air Conditioning systems (HVAC) provide an opportunity to reduce electricity and heat consumption and to limit CO2 emissions by 15–50%. The upgrade to the Sobieski Family Palace and the addition of new educational and administrative functions require state-of-the-art, energy-saving, and environmentally friendly solutions such as Fuel Cells and Hydrogen for Heating, Ventilation, and Air Conditioning (FCH HVAC) systems. As part of the program “Research for high-quality air in architecture and urban studies,” carried out since 2018 at the Institute of Architecture Planning, Department of Contemporary Architecture, Faculty of Civil Engineering and Architecture of the Lublin University of Technology, in 2021, further research was carried out in order to prepare for the potential implementation in 2022 of the project entitled “Development and Upgrade of the Former Sobieski Family Palace in Lublin. The main body of the building—educational and administrative function,” whose chief designer was Architect J. Wrana, Lublin University of Technology, 2021. The objective of this paper is to identify technologies and solutions specifically designed for HVAC systems in upgraded and renovated historic buildings. This paper is also a call for cooperation among institutions, scientists, higher education institutions, as well as an expression of appreciation for the immense energy stored in groundwater. This energy not only has the lowest carbon footprint but also is the only generally accessible large storage source from which we were unable to obtain ecologically pure energy before the introduction of FCH technology.

Experimental study on the feasibility and thermal performance of a multifunctional air conditioning system using surplus air thermal energy to heat a Chinese solar greenhouse

Maintaining a suitable temperature in the greenhouse in the cold season requires the assistance of the heating system, and renewable energy is advocated to replace traditional energy for greenhouse heating. To adjust the microclimate of the greenhouse, this study proposed a multifunctional air conditioning system that utilizes surplus air thermal energy (SATE), and the heat balance is used to calculate the system performance required for heating. Experimental results show that the system increased the minimum air temperature at night by 2.8 °C, and it also improved in continuous cloudy days, making the greenhouse temperature and humidity at night closer to suitable conditions, and the air temperature is more uniform in time and space. The provided heat energy and heat transfer rate of the multifunctional air conditioning system were 168.8 MJ/d and 4289 W, respectively, which were 95% of the Chinese Solar Greenhouse (CSG) heat demand and 50% of the CSG maximum heat load. Adjusting the temperature difference between water and air can also improve the heat release capacity of the system, and the system still has great potential. The multifunctional air conditioning system heating CSG is feasible, and the system is environmentally friendly and energy-saving, suitable for all kinds of greenhouses, and will have broad application prospects.

EVALUATION ENERGY SAVINGS AT MALUKU PROVINCE OFFICE BUILDING IN JAKARTA

The electricity is very important to support activities in office building .The equipment like AC ( Air conditioning ) needs more electricity to be operated. The is almost 60% is use to support this system (AC). This percentage describe that air condition system is an equipment that needs more electricity in the office and its become inefficiency in using electricity. To take overcome for this problem we need to efficiency in using energy. One of the method that now used to efficient that energy is called “ energy conversation” This method is using to saving the energy There is one thing that must be done in this activity which is “ energy audit “. Audit energy is one of method calculate IKE ( Intension Consumption Energy) at on the building.The first preliminary audit shown that more energy, which 60% is use to operated the air conditioning (AC) system and 30% to operate lighting system. IKE for the lighting system is still below from maximum standard which is 15 watt/m²The opportunity of saving energy on audit energy in AC system is done by cleaning up consist of : cleaning up filter, propeller corner fin of the evaporator, and the grill of in door unit.

Utilizing innovative proportional-integral-derivative controllers to reduce solar air conditioning system energy demand

In this study, a new proportional-integral-derivative controllers (PID) system was designed to analyze chiller energy demand (CED) in accordance with current criteria for lowering energy consumption in buildings (TED). By defining parameters of cooling setpoint (CSP) and cooling set back (CSB) schedule, the activity of the air conditioning system along with mechanical ventilation was adjusted well-ordered by the PID controllers. In the first step, it was found that a one-degree change in the CSP parameter had a much superior effect than a three-degree change in CSB. In this study, the heat recovery potential in Riyadh was evaluated and it was found that adding this system with a yield of 0.5 to 0.8, diminished TED in the range of 33.4 to 50%. With the development of a system of PID controllers, the economizer decreased CED by 1 kWh/m2 during CSB. Although the heat recovery system was much more successful than the economizer, to benefit the advantage of both devices simultaneously, a suitable PID system was designed to activate the economizer in CSB time and heat recovery in CSP. Due to the proper combination of these two devices, TED was reduced by 54.3%.

Utilizing the solar ice storage system in improving the energy, exergy, economic and environmental assessment of conventional air conditioning system

This paper introduces novel modification for conventional air conditioning systems through utilizing a thermal ice storage system integrated with solar panels. Alexandria and Aswan, cities in Egypt, are chosen to represent two climates for hot-humid and hot-dry climates respectively. Exergy analysis is performed for the proposed solar-ice thermal storage system based on transient analysis. Results showed that, the proposed system is more effective approach in hot-humid than hot-dry climate and more efficient with all-water system than with all-air system. The maximum energy saving is 205.16 GJ having a percent of 27.5% in August for all water system in case of Alexandria city and 224.67 GJ with a percent of 25.38% in August for all-water system in case of Aswan city. All air system simulation showed maximum energy saving of 175.05 GJ with a percent of 18.13 % in case of August for Alexandria and 175.45 GJ having a percentage of 17.43% in case of Aswan in August. Moreover, the all-water system achieved a reduction in CO2 emissions by 467 tons/year in Aswan city and 390 tons/year in case of Alexandria city. These reductions decrease to be 435 and 353 tons/year when the all-air system used for the same two cities.

Algorithm for searching optimal set values of absorption chiller system using Bayesian optimization

HVAC systems account for at least 40% of the energy consumption of general office buildings. Therefore, reducing the energy use of HVAC systems is indispensable. HVAC systems used in public office buildings mostly adopt a central air conditioning system. To save energy in the central air conditioning system, high-efficiency heat source machines have been adopted, and the inverter control of pumps has been generally introduced. As a further measure to save energy, an optimal control has been proposed. Model-based control has been mainly studied. However, the target HVAC system must be appropriately equipped with sensors for model-based control to use previous operation data. To solve this problem, we proposed a model-free optimal control method using Bayesian optimization. We verified its effectiveness in one-on-one (one cooling tower and one chiller) HVAC systems. As a result, the energy-saving ratio when compared to the rated specification control is 10.38% for our proposed method and 11.34% for the model-based approach, which shows the equivalent performance. In addition, the training results indicate that the optimal set values can be automatically determined in 4 weeks as the training proceeds under rated specification control with Bayesian optimization.

Determination of HVAC meteorological parameters for floating nuclear power stations (FNPSs) in the area of China sea and its vicinity

Floating nuclear power stations (FNPSs) are being constantly developed due to their potential for broad application. Meteorological parameters are an important basis for heating, ventilation and air conditioning (HVAC) system design and energy estimation. However, existing HVAC meteorological parameters are mostly applicable to inland buildings and are becoming obsolete due to climate change. This paper aims to determine the outdoor design temperature and relative humidity for FNPSs. Raw weather data recorded over a 30-year period from National Oceanic and Atmospheric Administration (NOAA) were used. Considering nuclear safety requirements and energy conservation goals, the HVAC meteorological parameters are classified into safety class parameters for nuclear safety-related systems and non-safety class parameters for conventional systems. In addition, the area of China Sea and its vicinity is subdivided into 18 sea regions to reflect local climate characteristics. For a typical FNPS, the outdoor design temperature proposed is compared with that provided in several standards from the perspective of cooling/heating load. It shows that cooling and heating loads with safety class design temperature are 34.0% and 26.5% less than the maximum design cooling and heating loads, respectively. This study can serve as a reference for the determination of HVAC meteorological parameters of FNPSs.

Air damper with Controlling Capacity Unrelated to duct system resistance

The air volume control performance has an important impact on Heating, Ventilation and Air Conditioning (HVAC) system energy efficiency, indoor air quality and thermal comfort. However, one of the challenges in researching the air volume control of HVAC systems is that the controlling capacity of air dampers is related to the resistance of the entire duct system. The working flow characteristic (WFC) curve of the air damper varies across different duct systems, which strongly affects the damper control performance. Therefore, for this problem, this paper employed the combined CFD numerical simulation and experimental verification to obtain a novel air damper and its controlling formula. The novel air damper has good controlling capacity, and its flow characteristic curve does not change with the difference of the duct system. This paper offers a reference for the hydraulic balance of ventilation and air-conditioning systems and provides a new perspective for precise air volume control.

Energy and exergy analyses of a transcritical CO2 air conditioning system for an electric bus

Abstract The cooling performance of a transcritical CO2 air conditioning system for an electric bus was investigated using energy and exergy analyses. The effects of the working conditions, such as the compressor speed, electronic expansion valve (EEV) opening, inlet temperature and flow rate of indoor air and the inlet temperature of outdoor air on the energy performance were experimentally investigated. Exergy analysis of the system was performed based on the experimental data. Experimental results showed a coefficient of performance (COP) of 2.88 and a cooling capacity of 31.4 kW at a condition of 35 °C/27 °C (an outdoor air temperature of 35 °C and an indoor air temperature of 27 °C). As the outdoor air temperature increased to 45 °C, a COP of 1.87 was achieved with a cooling capacity of 22.8 kW. Therefore, the system possessed a good cooling performance in hot climates. Increasing the indoor air flow rate could improve the exergy efficiency of the system and increasing the indoor and outdoor air temperatures could reduce the exergy efficiency of the system. Among the exergy destructions of the components, the values obtained for the gas cooler and EEV accounted for significant proportions, offering great opportunities for improving the system performance. In extremely hot climates the exergy destruction of EEV comprised the greatest percentage and further research should be performed on the significant throttling loss of the expansion process.

Multi-objective optimization design of green building envelopes and air conditioning systems for energy conservation and CO2 emission reduction

Configurations of the building envelope and the air conditioning system have a considerable effect on annual building energy efficiency. Taiwan government proposed two green building indices, namely the Envelope Energy Load (ENVLOAD) and the Performance of Air Conditioning System (PACS), as energy performance models of building envelopes and air conditioning systems. Relatively few studies, however, have been mainly conducted, using multiobjective optimization design for building envelope and air condition systems, with a goal to treat both the building energy systems and the envelope. Consequently, this study is to make contribution to this related filed by proposing a multi-objective optimal building envelope and air conditioning system energy performance decision model (MOBELM).This model was used to design the optimal configurations of building envelopes and air conditioning systems based on the ENVLOAD and PACS constrictions and the two conflicting objectives. The first refers to the minimal construction cost when the building envelope and air condition system are built. The second is concerned with the minimal CO2 emission when the envelope materials are manufactured and used to form the building envelope. In the case study, the optimized configurations that dominated the original unoptimized design could validate the MOBELM.