Air Conditioning Load Research Articles

Research on Air-Conditioning Cooling Load Correction and Its Application Based on Clustering and LSTM Algorithm

Climate change and urban heat island effects affect the energy consumption of buildings in urban heat islands. In order to meet the requirements of engineering applications for detailed daily design parameters for air conditioning, the 15-year summer meteorological data for Beijing and Shanghai and the corresponding average heat island intensity data were analyzed. Using the CRITIC objective weighting method and K-means clustering analysis, the hourly change coefficient, β, of dry bulb temperature was calculated, and the LSTM algorithm was used to predict the changing trends in β. Finally, the air conditioning load model for a hospital was established using DeST (version DeST3.0 1.0.2107.14 20220712) software, and the air conditioning cooling load in summer was calculated and predicted. The results show that, compared with the original design days, regional differences in the new design days are more obvious, the maximum temperature and time have changed, and the design days parameters are more consistent with the local meteorological conditions. Design day temperatures in Shanghai are expected to continue rising for some time to come, while those in Beijing are expected to gradually return to previous levels. Among hospital buildings, the cooling load of outpatient buildings in Beijing and Shanghai will decrease by 0.69% and increase by 12.61% and by 12.12% and 15.51%, respectively, under the influence of the heat island effect. It is predicted to decrease by 1.35% and increase by 29.75%, respectively, in future. The cooling load of inpatient buildings in Beijing and Shanghai increased by 0.27% and 6.71%, respectively, and increased by 7.13% and 8.09%, respectively, under the influence of the heat island effect, and is predicted to decrease by 0.93% and increase by 16.07%, respectively, in future.

Numerical and experimental investigations on melting heat transfer performance of PCM in finned cold thermal energy storage

Cold thermal energy storage (CTES) is of great importance for the enduring decrease in fossil fuel energy consumption. Moreover, CTES with phase change materials (PCMs) can be an effective measure to accumulate the heat or cooling energy for overcoming the mismatch between the supply and demand of air conditioning loads, augmenting system dependability and flexibility in operations of power grids. This paper numerically and experimentally examines the melting characteristics of PCM inside a CTES tank with the installation of interior fins. The computational fluid dynamics (CFD) software ANSYS/Fluent® is applied to predict the time sequences of liquid fraction contours and temperatures in comparison with the photographed images of ice-liquid water interface and measurement data in the CTES tank to verify the accuracy of CFD predictions. The simulations by the validated CFD model are extended to evaluate the influences of fin height and total number of longitudinal fins on the heat transfer outcomes in the storage tank. The present study further proposes a novel design adopting stratified fins to enhance the melting performance of the CTES device. The estimated mean power with the new stratified fin design is notably greater than that without fins by 156.3%, achieving the effectively liquefaction enhancement of ice for guiding the development of finned cold thermal energy storage.

Micro-Grid Day-Ahead Stochastic Optimal Dispatch Considering Multiple Demand Response and Electric Vehicles

Multiple demand responses and electric vehicles are considered, and a micro-grid day-ahead dispatch optimization model with photovoltaic is constructed based on stochastic optimization theory. Firstly, an interruptible load model based on incentive-based demand response is introduced, and a demand response mechanism for air conditioning load is constructed to implement an optimal energy consumption curve control strategy for air conditioning units. Secondly, considering the travel demand and charging/discharging rules of electric vehicles, the electric vehicle optimization model is built. Further, a stochastic optimization model of micro-grid with demand response and electric vehicles is developed because of the uncertainty of photovoltaic power output. Finally, the simulation example verifies the effectiveness of the proposed model. The simulation results show that the proposed model can effectively tackle the uncertainty of photovoltaic, as well as reduce the operating cost of micro-grid. Therefore, the effective interaction between users and electric vehicles can be realized.

Analisa Perhitungan Beban Pendingin Ruangan Di Komplek Glamour Mansion Tanjung Morawa Mengunakan Aplikasi Cooling Load Daikin

Air conditioning for residential comfort is important for human life for the early days of the changing weather climate that affects the temperature of the air temperature in residential dwellings. The air conditioning system is one of the business actions in the form of maintaining the temperature level in the room from the low level of the ambient temperature around it by absorbing heat from the material or room. The air conditioning load is also carried out to determine the AC capacity needed. Research conducted by the Glamour Mansion Tanjung Morawa Housing Complex using the method used to calculate cooling capacity based on GA (General Arrangement) which includes several parameters, namely the number of people, number of windows, room volume, equipment, and heat from lights. So that the calculation of Heat Calculation, Air Capacity, and Cooling Capacity in a complex is obtained. From the results of the study it is known that the AC cooling load for the Glamour Mansion Tanjung Morawa Complex is the living room 1482 BTU / h, Room I 1953 BTU / h, Room II 800 BTU / h. 1 AC with a capacity of ½ PK in the room. 1 AC with a capacity of ½ PK in each room

Insulation Performance of Building Components and Effect on the Cooling Load of Homes in Saudi Arabia

A common practice in the construction of residential and commercial buildings in Saudi Arabia is to insulate the outer walls and windows only. Other building components such as the roof, columns and slabs, and doors are usually neglected. Moreover, vital components such as the roof and windows are especially neglected in commercially built residential and commercial buildings. The aim of this study is to put this common impression and practice to the test by quantifying the contribution of every building component to the overall air-conditioning load of the building. The hypothesis evaluated in this paper is that despite the common practices, there could be an optimum selection of insulators for the building components that yields the lowest energy consumption and maximum savings not only in energy costs but also installation costs. The required air-conditioning load is determined using manual calculations and the HAP software package for 1022 possible configurations. The findings of the analysis point to the importance of the roof, as it is the major contributor to the thermal load, followed closely by columns and slabs, with 44.2% of the overall cooling load. It is found that a single wall consisting of 2 cm of cement plaster, 20 cm of cement–polyurethane brick, and 2 cm of cement plaster is less expensive and has higher thermal resistance than any of the more expensive double walls. The study found one scenario of possible configurations with the optimized selection of building materials and their insulation materials that provides the most effective insulation at the lowest cost.

Investigation of vertical thermal stratification and stratified air conditioning load for large space with low-sidewall supply air based on vertical temperature node model

Large space buildings often use stratified air conditioning, which has the advantages of reducing energy consumption and improving indoor air quality. The airflow pattern of low-sidewall supply air is a common technology for creating stratified air conditioning in large space. The vertical temperature dynamic distribution is a momentous feature in stratified air conditioning thermal environment, and it is also the key to attain energy saving. In order to explore the heat transfer evolution process for large space stratified air conditioning, a vertical temperature node model for predicting the thermal stratification was established based on the airflow pattern of low-sidewall supply air. In this node model, the large space indoor environment is divided into several air layers in the vertical direction. Each air layer is considered about the aspects of wall convection heat transfer, supply air heat transfer, airflow heat transfer between air layers, temperature differences heat transfer between air layers and so on. A series of heating balance equations are established, and the vertical temperature dynamic distribution results can be obtained by matrix iterative calculation. Based on the 24-h periodic heat flow, the calculated results of the node model were compared with the experimental results. Then, based on the vertical temperature node model, the heat transfer evolution process and dynamic cooling load calculation of large space stratified air conditioning with low-sidewall supply air were discussed and investigated quantitatively.

Energy advantage of cold energy recovery system using water- and air-side free cooling technologies in semiconductor fabrication plant in summer

The semiconductor industry requires large amounts of energy. Of the total energy, semiconductor manufacturing facilities consume the most electricity, where 21–29% of the total energy is used to maintain a clean room environment at a constant temperature and humidity. The energy required for constant temperature and humidity has been developed and applied in various ways, e.g., waste heat recovery technology without a boiler. However, it is highly difficult to obtain the energy required for cooling without operating a chiller unless there is a climatic advantage. Therefore, with the perspective of introducing cold energy recovery system into outdoor air-conditioner, this paper suggests the analysis of the energy-saving effect of the recovery system which recovers wasted cold energy of the exhaust gas from the semiconductor fabrication plant located in high-temperature and humid region. Two systems have been proposed: a water-side free cooling system that recovers cold energy by connecting a cooling tower to exhaust gas, and an air-side free cooling system that recovers cold energy by connecting a membrane energy heat exchanger. When applied to the conventional outdoor air-conditioner after cold energy recovery in both systems, the energy-saving effect was estimated by a simulation program (i.e., engineer equation solver) using a theoretical calculation model. The result showed that the cooling load of the outdoor air-conditioner decreased by 10.2–13.1% and 8.5–11.2% when the water-side free cooling system and air-side free cooling system, respectively, were applied at an exhaust gas temperature of 24–28 °C and a humidity ratio of 0.00733 kg/kg’. However, with the consideration of the power consumed by the cold energy recovery system (i.e., water/air-side free cooling system), actual energy-saving rate was low. Consequently, the head and static pressure designs of the fluid transfer equipment (i.e., pumps and fans) of the cold energy recovery system should be considered with caution when the cold energy recovery system is applied.

Energy consumption calculation of campus buildings based on the law of personnel flow

AbstractFor a certain functional building group, the coupling relationship between the load of a single unit and entire building groups lies in the spatial and temporal patterns personnel distribution. Using the DeST (Designer's Simulation Toolkit) method, the personnel flow trajectory in a university campus in Shanghai was analyzed and the established energy consumption calculation model based on personnel flow trajectory of university buildings. It is proposed that personnel mobility should be included in the application of DeST to predict the total load of building groups. The results show that after the people flow trajectory was included, the total annual accumulated load decreased from 27.01 to 19.39 GWh, reducing by 28.20%; the hourly load fluctuation became more stable, the daily peak load decreased by 22.57%, and the daily peak valley difference decreased by 43.74%. The results suggest that the prediction for the air conditioning load of building complexes would be better when the trajectory of human flow is considered, minimizing unnecessary system scale and investments. Under the “double carbon” policy, the personnel flow trajectory model can effectively reduce waste in air conditioning energy consumption in campus buildings.

Performance investigation of solar assisted desiccant integrated Maisotsenko cycle cooler in subtropical climate conditions

Air conditioning has become an integral part of buildings due to climate change and global warming. About 40% of the world energy is being consumed by the building sector, with around 50% share of HVAC applications. In the current study, the simulation-based performance of solar desiccant integrated Maisotsenko cycle cooling system is analyzed in subtropical climate conditions. Initially, an office building model is developed in TRNBuild to generate hourly dynamic year around air-conditioning loads. Afterwards a simulation model of the SDI-MC is developed for maximum cooling capacity of 24 kW in TRNSYS and validated with experimental data. Additionally, an effective control strategy is also implemented to efficiently meet the air-conditioning demand. The main performance parameters include COP, cooling capacity, useful energy gain, efficiency of solar water heating system, auxiliary energy share, and solar fraction of the system. The result revealed that the COP of the system ranges from 0.78 to 1.13 due to variation in system inlet humidity and temperature. Regeneration temperature requirement varies from 60 °C to 78 °C while cooling capacity of system ranges from 8 KW to 24 KW. Similarly, the results revealed an average annual efficiency of evacuated tube solar thermal collectors around 35.80% with total annual energy gain of 113.96 MJ. Furthermore, the maximum annual auxiliary energy share required for regeneration is 12.5%.

Effect of local climate zone (LCZ) and building category (BC) classification on the simulation of urban climate and air-conditioning load in Hong Kong

Reliable energy models are required to predict urban-scale air-conditioning (AC) load under extreme outdoor temperatures which is crucial to power security. In this study, we proposed a new landuse/landcover (LULC) scheme for these models by combining the local climate zones (LCZs) from World Urban Database Access Portal Tools (WUDAPT) and building category (BC) map. Apart from evaluating against the conventional LULC of Moderate-resolution Imaging Spectrometer (MODIS) and WUDAPT, the impact of urban canopy parameters and BC on the simulated meteorological conditions and AC load during the 2016 heatwave in Hong Kong was examined by the Weather Research and Forecasting (WRF) model. Incorporating LCZs (BC) reduced the bias of 2-m temperature (T2), 2-m relative humidity (RH2), and AC load intensity by 0.4 °C (2.0 °C), 1.98% (0.68%) and 6.78 W m−2 (13.09 W m−2), respectively. It captured the heterogeneous, intra-urban T2 and turbulence kinetic energy (TKE). Further sub-classifying the BC in LCZs led to WUDAPT/BC which performed even better and significantly improved WRF output. It simulated well the daytime wind speed, mitigated the overprediction (underprediction) of T2 (RH2), and rectified the underpredicted AC load in WUDAPT. Its benefit was prominent in daytime as well as in compact high-rise/mid-rise and open high-rise areas. (200 words).

EFFECT OF INTERNAL INSULATION LAYER USING NON-LIVING ROOM OF DETACHED WOODEN HOUSE ON AIR CONDITIONING LOAD

In order to increase thermal insulation performance of wooden detached house in a temperate region considering various plans and lower cost, new insulation techniques utilizing internal layers including non-residential spaces, partitions and ceilings without increasing the thickness of insulation in exterior wall were proposed. The six types of two-story house models using internal insulation layers with almost the same floor area but different plans were proposed and were clarified each air conditioning load by numerical simulation. It was confirmed that the thermal insulating effect could be enhanced by insulating the internal layers.

Global performance analysis of a solar-driven indoor CO2/H2O capture system for air quality enhancement and cooling energy saving

A human-eco-friendly building requires high indoor air quality (IAQ) and low carbon emissions. Existing natural/mechanical ventilation methods rely on frequent exchange with fresh ambient air to remove excess respiratory CO2 for high IAQ. However, in tropical or subtropical regions, the introduced ambient air features higher humidity and temperature over indoor air, which inevitably increases the energy burden of air conditioning (AC) accompanied with severe CO2 emission. To circumvent this paradox, this study developed a dynamic solar-driven indoor CO2/H2O capture system with selective air recirculation. Rather than simply introducing ambient air to reduce indoor CO2 concentration, this scheme actively captures CO2/H2O and selectively returns post-captured air with sub-ambient temperature, relative humidity and CO2 concentration, thus sustaining high IAQ with reduced AC load and CO2 emission. The system’s feasibility and stability are demonstrated through a 20-city global study and a 10-variable sensitivity analysis. Compared to traditional methods, this new system could save up to 64 % of cooling energy while maintaining the indoor CO2 concentration below 1000 ppm and relative humidity within 25 %-55 %. The energy-saving potential of the proposed system increases in regions with larger AC demands, as evidenced by Dakar achieving the highest energy-saving potential and thus decreasing CO2 emission. This system could further reduce CO2 emission by direct capture and storage, whose amount is positively correlated to the amount of solar irradiance in cities. Furthermore, the system demonstrates robustness under off-design conditions and is flexible to be scaled up/down. Overall, this study provides effective-green ventilation strategies and paves the way for developing human-eco-friendly buildings.

Analisa Audit Energi Listrik di PT. Ispat Bukit Baja Kota Bekasi

PT. Ispat Bukit Baja is a company engaged in the steel production industry. Every component production uses electricalenergy as the main source. With the main load of lighting, air conditioning, and electric motors, the use of electricity in this company is verylarge and important. An audit energy needs to be carried out because the value of Energy Consumption Intensity in 2020 is 251 kWh / m2/ year and in 2021 it is 221 kWh / m2 / year and the value of Specific Energy Consumption in 2020 is 0.26 GJ / Ton and in 2021 is 0.29GJ/Ton. The energy audit method used is to calculate the value of Energy Consumption Intensity and Specific Energy Consumption. Thesavings opportunities made are on the air conditioning system, lighting system, and electric motor load. From the results of the analysisand calculation of savings in the air conditioning system, savings of 50.1% or 67.70 kWatt were obtained using a psychrometric diagramto determine the cooling system according to the needs of the room, then for the lighting system, savings of 21.9% or 6 kWatt by replacingthe installed lighting system with energy-saving lamps, then the load of the electric motor is using capacitor to improve the power factorvalue which was originally 0.77 to 0.85 with the aim that the motor speed does not change which will result in the precision of the productionobtained savings in the use of apparent power of 7.13% or 126.52 kVA. So that the results of the apparent power savings can be used forbackup. The total recommended power saving obtained from the calculation results is 73.7 kWatt. So based on the calculation of the energyaudit that has been done, it can reduce production costs and energy use efficiency

A stochastic interior disturbance parameter model considering double uncertainty for probabilistic load calculation

The probabilistic method of calculating air-conditioning design load can effectively solve the oversizing problem in the deterministic method. However, the realization of the probabilistic method requires the quantification of the uncertain input parameters. Among them, the interior disturbance parameters are the key, whose uncertainties are caused by the unknown nature of interior configuration and the randomness of interior disturbance fluctuations. A stochastic interior disturbance parameter model considering double uncertainties (referred to simply as the DUSP model) was thus proposed. In this model, the uncertainty in the interior disturbance design parameters and interior disturbance time coefficients, which comes from two different sources, are described using probability distributions and occupant behavior models respectively. On this basis, the time series of interior disturbance parameters are generated by random sampling, to characterize the uncertainty of the interior disturbance parameters. Comparing the DUSP model with two models considering single-source uncertainty, the results showed that in the probabilistic load calculation, neglecting the uncertainty of the interior disturbance time coefficients may result in an overestimation of the design load by up to 9.2%; neglecting the uncertainty of the interior disturbance design parameters may result in an underestimation of the design load by up to 2.5%. Therefore, it is necessary to quantify the uncertainty in both sources simultaneously to ensure the reasonableness of the probabilistic load calculation.

Investigating energy efficiency and solar energy in Saudi mosques to achieve zero energy or zero bill

Energy is essential to achieve thermal comfort; however, energy consumption leads to environmental degradation. This study analyzed the energy consumption of two masjids in the Kingdom of Saudi Arabia (KSA) and identified opportunities for rationalizing energy consumption. A photovoltaic (PV) system was used to ensure that the conditions of nearly zero bill building (nZBB) or nearly zero energy building (nZEB) were fulfilled. The energy use intensities of the Al-Jamil and Al-Omar masjids were 111 kWh/m2 and 121 kWh/m2, respectively. The average electricity consumption per worshiper for the Al-Omar masjid was 1.35 kWh/prayer and that for the Al-Jamil masjid was 1.03 kWh/prayer. The end-use energy was the highest for cooling, accounting for 72–74 % of the total consumption; lighting accounted for 11–12 % of the total consumption at the two masjids. Approximately 60 % of the air-conditioning (AC) energy load was saved by improving the envelope; the electricity requirement for ACs increased by up to 30 % as the ambient temperature increased from 32 °C to 46 °C. Changing the set-point temperature from 20 °C to 27 °C afforded electrical energy savings of approximately 27 % for a summer day. The environmental benefits of using solar energy were also identified.

Distributed robust dispatch for the coordination of transmission and distribution systems considering air conditioning loads

The coordinated operation of the transmission system (TS) and connected distribution systems (DSs) is momentous for handling the increased penetration of distributed energy resources (DERs). This paper presents a distributed dispatch framework for the collaborative yet independent operations of TS and DSs. Only two kinds of boundary coupling variables, active power and reserve capacity, are exchanged to implement the sharing of energy and reserve among different systems with the information privacy preserved. Then, a distributed robust energy and reserve dispatch approach is proposed, wherein the flexible resources in different systems are coordinated in the normal and uncertainty cases to enhance the overall economic efficiency and reliability. Apart from generation resources, air conditioning loads integrated by the aggregated virtual energy storage (AVES) model are incorporated. And the reserve model of AVES with the state-switch-feasibility constraints is developed to fully exploit the flexibility of air conditioning resources, which can be compatible with the optimal scheduling of existing systems. Case studies on three test systems verify the effectiveness and superiority of the proposed method.

Adaptive power load restoration considering flexible control of air conditioners for resilience enhancement

Frequent extreme hot weather brings a surge of air conditioner load and further increases the probability of outages. Fitting to different power grid operating conditions and outage scenarios, an adaptive load restoration strategy is proposed, which can take full use of flexible control of air conditioners and reliable power sources from the power grid and distributed generations or microgrids. Considering the influence of outage duration and environmental temperature, an air conditioner aggregated power estimation model is established to evaluate the cold load pickup amount. Based on the allowable maximum load pickup amount, a load pickup amount reduction method by flexible control of air conditioners considering the impact degree on the customer is proposed to guarantee secure load pickup operation. Simulation results of the IEEE 14-bus system and a practical power grid demonstrate that the proposed method can restore the power supply of customers rapidly and securely to enhance power grid resilience under extreme hot weather.

A novel approach to estimate power demand of auxiliary engine loads of light duty vehicles

On par with rapid motorization, excessive energy demand and air pollution have become major challenges in the global context. Fuel economy programs and emission reduction targets have proven to be among the most effective in mitigating these issues. In developing successful fuel economy programs and policies, understanding the factors affecting the fuel consumption of road vehicles is essential. Auxiliary engine loads are one of the commonest factors affecting a vehicle’s fuel economy performance. An auxiliary engine load is defined as the energy utilized to operate auxiliary equipment that draws its power from the vehicle’s engine. This study was limited to light duty vehicles, and an analytical method was adopted to assess the fuel economy impact of the auxiliary equipment in terms of air-conditioning load, alternator load, and water pump and steering pump load. As one of the main deliverables, the study developed a novel approach for estimating and modeling the air-conditioning load which is the major auxiliary energy consumer. For an average car of 100 brake horsepower (bhp) (74.7 kW), the engine auxiliary equipment consumes approximately 13.130 kW of power at an engine operating speed of 3,000 RPM, which amounts to 17.6% of the total bhp output. The major contributors to engine power demand are the air-conditioning unit and the alternator, which account for over 97% of the total auxiliary power requirement, while the water-pump and power steering-pump use relatively little power at 3% of the total auxiliary power demand. The novelty of the method adopted during this study is that it theoretically determines the major contributor of the auxiliary power demand, the air-conditioning load, whereas prior reports have used approaches involving empirical methods.

Analysis of the rule of window-to-wall ratio on energy demand of residential buildings in different locations in China

Building energy demands are influenced by the window-to-wall ratio (WWR). The impact of the WWR on the energy demand in the same area has been researched by software. However, the impact of the WWR on the energy demand of buildings in different locations of China has not been investigated using the energy balance equation. The equation for the indoor temperature variation under various internal and external disturbances was provided in this study. The relationship between parameters A and B and the change in indoor temperature was proven. China's Harbin, Beijing, and Chengdu air-conditioning and heating loads, as well as the impact of changing WWR on the rate of energy savings for air-conditioning and heating energy demand, were studied. After investigating the changes in the cooling and heating loads in various cities under various WWRs, the suitable relationship between the cooling and heating loads and the WWR of three urban units was discovered. The findings indicated that despite the three cities' various climates and the diverse energy demands for air conditioning and heating in each city, with the same change in the WWR of urban buildings, the change rate of the air conditioning and heating loads in each city was near. Meanwhile, the heating and cooling loads were linear with WWR.

Effect of existing residential renovation strategies on heating and cooling load in Shanghai

To provide a reference for the renovation of Shanghai’s existing residential districts, this study quantifies and compares the relationships between common renovation strategies, microclimate, heating and cooling loads. These common strategies include improving the greening rate (G), improving the reflectivity of pavement (P), improving the reflectivity of wall materials (W), and improving the reflectivity of roof materials or applying green roof (R). These strategies are applied to a typical model extracted from existing residential areas in Shanghai, China. ENVI-met and EnergyPlus are combined to simulate the microclimate represented by the average meteorological parameters in front of building surfaces and the building heating and cooling load on a typical meteorological day in winter and summer. The results show that applying microclimate data around target building contributes to a significant difference in air conditioning load in both summer and winter. For summer, G, W, and R reduced their total cooling load, whereas P increased this parameter. R contributed the most significant decrease in the total cooling load, followed by W, and G contributed the least. G3P1W3R3 and G1P3W1R1 were the scenarios with the lowest and highest cooling load. The total cooling load under G3P1W3R3 was 136 kWh (12.7%) less than that under G1P3W1R1. For winter, P and applying green roof (R4) reduced the heating load of the target building, whereas G, W and improving roof reflectivity (R2, R3) increased it. G1P3W1R4 and G3P1W3R3 were the scenarios with the lowest and highest heating load. The heating load under G1P3W1R4 was 145 kWh (14.5%) less than that under G3P1W3R3.