Air Conditioning Water Research Articles

Application Potential of a Dew-Point Cooling Tower in Selected Energy Intensive Applications in Temperate Climate

In the article, the application potential of the dew-point cooling tower (DPCT) in selected energy-intensive applications in temperate climates was analyzed and discussed. The applications selected for analysis are power generation with natural gas turbines and chilled water air conditioning systems. The study is based on a mathematical model derived from a modified ε-NTU model. The model was validated against experimental results and showed satisfactory agreement with the experimental data. DPCT was compared with a typical cooling tower limited by the wet-bulb temperature (wet-bulb cooling tower, WBCT). The simulation results showed that DPCT is able to provide significant energy savings in energy-intensive applications; therefore, its application potential in temperate climates can be considered justified. In the case of gas turbines, DPCT was able to generate 2 to 10 percentage points more capacity than operating on outdoor air and 1.8 to 5 percentage points more than operating with WBCT. In the case of air conditioning systems, the system equipped with DPCT achieved EERs (energy efficiency ratios) higher by 1 to 7.2 compared to dry cooling and by 0.3 to 5.1 compared to systems equipped with WBCT. The annual energy savings obtained by the system with DPCT were 14.7 MWh compared to WBCT and 30 MWh compared to dry cooling.

Hybrid model-free control based on deep reinforcement learning: An energy-efficient operation strategy for HVAC systems

At present, most optimization objectives of heating, ventilation, and air-conditioning (HVAC) systems focus on the local optimization of equipment during cooling hours, usually ignoring the importance of the end conditions. In addition, traditional control methods may not perform well in complex or dynamic systems. Therefore, in this study, a hybrid model-free control (HMFC) strategy was developed that combines deep reinforcement learning (DRL) with L-BFGS-B and expert knowledge to improve its ability to cope with complex system environments. This strategy was used to optimize the cooling and heating periods of a groundwater source heat pump system in a bitterly cold region of China throughout the year, considering the end-of-system conditions. L-BFGS-B optimized the fresh-air ratios for the end air-handling unit, whereas DRL achieved global optimization of the heat pump outlet temperature, air-conditioning water circulation pump frequency, and submersible-pump frequency. To verify the effectiveness of the strategy, a simulation platform was built based on actual data and device parameters, and the simulation results of HMFC and model predictive control (MPC) were output, compared, and analyzed with data of the system measured in 2022 under expert rule-based manual control (RBC). The results show that HMFC was 7.38 % and 9.38 % more energy efficient than RBC during heating hours, respectively. HMFC was 24.26 % more energy efficient than RBC and 10.03 % more energy efficient than MPC during cooling hours. Moreover, the distribution of the system coefficient of performance under the HMFC method was more concentrated in the higher range, indicating that the proposed HMFC can save energy savings. Thus, it is a feasible optimization scheme for buildings without a large number of historical data. Finally, the strategy was applied to a real engineering experimental analysis, and the engineering practice results show that the strategy is robust and practical.

Comparative analysis of energy efficiency for three heating and cooling supply schemes in a region with hot summers and cold winters in a chemical industrial park

Building energy consumption in China accounts for 45% of the total national energy consumption, with air conditioning energy consumption representing approximately two-thirds of that. Therefore, energy efficiency in buildings is of utmost importance. This study focuses on a chemical industrial park located along the Fujiang River and compares three heating and cooling supply schemes: the river water source heat pump system, which utilizes river water as the heat source and heat sink; the water cooling unit and boiler system, which uses water-cooled electric compression chillers for cooling and an oil-fired boiler system for heating; and the split air conditioning and gas water heater scheme, which relies on refrigerants such as fluorine-containing compounds for cooling and a gas water heater for heating. By calculating the energy consumption of the above three schemes and conducting a comparative analysis, it is found that the river water source heat pump system exhibits significantly higher energy efficiency throughout the year compared to the water cooling unit and boiler system and the split air conditioning and gas water heater scheme. This highlights the notable energy efficiency advantage of the river water source heat pump system.

Exploring the perceptual experiences of nurses regarding the care of patients with COVID-19: A mixed methodological approach

Abstract Background: The COVID-19 pandemic, with its rapid spread and subsequent lockdown measures, has brought about unprecedented changes in our lives. Terms like lockdown, social distancing, and quarantine have become part of our daily vocabulary. Amid this crisis, frontline workers, including nurses, have emerged as the unsung heroes, bravely battling the effects of the pandemic. This study delves into the perceptual encounters of nurses regarding patient care during this critical period, providing valuable insights into their experiences. Materials and Methods: This study employed a unique mixed-methods sequential explanatory design. Quantitative data was gathered from 202 registered nurses attending to COVID-19 patients in designated hospitals in Navi Mumbai. Following quantitative analysis, samples of qualitative data were collected until data saturation, focusing on experiences categorized as fair or adverse. Quantitative data collection relied on self-reporting, while qualitative data collection involved in-depth telephone interviews and audio recording techniques. The study’s scope was confined to hospitals in Navi Mumbai and specifically targeted staff nurses providing care for COVID-19 patients. Results: 39% of respondents reported experiencing fair situations, while 69% of nurses expressed encountering negative experiences related to COVID-19. The study identified various themes, including encountered challenges, physical hardships, emotional conflicts, provided facilities, and most importantly, the robust support systems. Challenges included caring for immobile patients, insufficient staffing, and extended work hours. Mental concerns comprised fear of contracting the virus, stress, familial tensions, separation anxiety, and disrupted communication with loved ones. The provided facilities encompassed meals, transportation, lodging, personal protective equipment, and amenities such as air conditioning and hot water. Support was observed from colleagues, friends, family, and senior staff members, highlighting the strength of the healthcare community in times of crisis. Social resistance included pressure to resign, lack of familial support, and societal stigma. Coping mechanisms involved communicating with loved ones, receiving support from colleagues, and engaging in activities such as listening to music, meditation, prayer, exercise, and yoga. The study found no significant association between nurses’ perceptual experiences and selected demographic variables. Conclusion: The study examined the perspectives of staff nurses regarding their duties during the COVID-19 pandemic, capturing their experiences through quantitative and qualitative analyses that addressed notable challenges, including physical, mental, and social obstacles.

Performance evaluation of solar-activated integrated double-stage water desalination and air conditioning plant

The condenser's rejected heat in a vapour compression refrigeration system when thrown into the surrounding air results in its thermal pollution and gets wasted, while it has the potential to be recovered. Another major targeted concern is freshwater scarcity which is faced by the population in many areas. Addressing these difficulties, a double-stage integrated humidification-dehumidification and air conditioning system that recovers the condenser's waste heat and is assembled in a novel duct architecture is proposed. The obtained results of the developed model are established using the experimental data. The analysis explores the outcomes of the integrated system and investigates the influences of saline water temperature, humidifier efficiency, ambient temperature, and relative humidity on the output and performance metrics. The system provides air conditioning of 31.410 kJ and desalination of 65.020 mL from a unit volume of air using 0.661 kW of power and mitigates the environmental impact of existing technology. The coefficient of energy performance, cooling performance, gained output ratio, and exergy efficiency at the specified working situations are 0.958, 1.320, 6.809, and 2.701 %, respectively. A litre of freshwater costs $ 0.0068486.

Design standards for residential N-ZEBs in mild Mediterranean climate

In this paper the authors intend to investigate into the possibility of obtaining the Net Zero Energy Building (N- ZEB) standard for a residential building type widespread in Mediterranean climate. To this aim, the study considers a terraced-house apartment building with an external envelope made of clay blocks and concrete structure, which is a very common solution in Italy. At first, the building is thought to be designed according to the current national regulations concerning the insulation level of the envelope; for such configuration, the current energy needs for heating, air conditioning, lighting and hot water production are calculated through dynamic simulations tools. Then, the study discusses the interventions, both on the envelope and on the energy systems, needed to transform this conventional building into an N-ZEB, avoiding excessive modifications to its design. Due to the diffusion of this typology, the case considered in the paper is very representative, and the conclusions might be extended to a significant portion of the building real estate. The final aim is to define a construction standard that might become a reference for the design of future residential N-ZEBs in Mediterranean countries.

Distributed Generation of Energy Using Micro Gas Turbines. Polygeneration Systems and Fuel Flexibility.

The use of micro gas turbines (MGT) for on-sitesmall-scale energy production offers a great opportunity forprimary energy saving and reduction of pollutant andgreenhouse gas emissions. These benefits mainly come from thepossibility to locally recover waste heat from exhaust gasespecially for air conditioning thermally activated technologlesand also for their capability to use low heating value gases suchdigester gas. This paper summarises the potential of' micro gas turbines indistributed generation systems to simultaneously producepower, heat and chilled water for air conditioning. Differentconfigurations for coupling micro gas turbines and sorptionsystems will be presented from the conventional hot waterdriven to the directly exhaust gas driven configurations. Themain advantage of these systems is the consumption of wasteheat for refrigeration and air conditioning instead of high costelectricity. On the other hand the use of digester and landfill gas in microgas turbines is very attractive from many points of' view:reduced electrical bill, higher energy efficiency due to on-siteheat recovery, reduction of odours and lower greenhouseemissions. The processing of pig manure to produce biogas isof high interest in geographic areas with a surplus of manurethat can not be naturally absorbed and limits the growth of farmsites. In this paper it is presented a summary of' the state of' theart for the use of biogas in microturbine based cogenerationsystems along with a brief description of the different types offuels that can also be used in microturbines.

Women roles for saving energy and net-zero emissions for solar energy

Climate change and energy issues for saving, consumption, and renewability suffer from illiteracy and ignorance. In the patriarchal society like Indonesia, women performed vital roles in the households. Women can play strategic roles as agents of change i.e. transformation of energy sectors and decision makings. Indonesian Directorate General of Mineral and Coal launched regulation 26/2021 stated that household sector is the main consumer targets for solar energy plant using grid connected. The facts showed middle-high income’s households unlikely install solar panel. Electricity motorcycles and cars do not mean so much when the batteries must be charged with non-renewable sources. Meanwhile, the heat in Pekanbaru is abundance and has potential for solar energy. The research will elaborate perception of 20 educated person and 10 career women on how their energy consumption and the possibility of solar panel usage in their houses using in-depth interviews. The research showed women in Pekanbaru spent at least a half million even two million rupiah per month, especially for air conditioning and hot water. The lack of knowledge of solar energy and solar plant installation led to women roles indecisive.

Benchmarking green technologies: a survey of non-domestic buildings in Sri Lanka

The escalating demand for energy and resources in the construction industry, together with poor energy performance of existing buildings, pose challenges for sustainability. Despite the incorporation of advanced technologies in modern construction to reduce energy consumption, a significant number of buildings are yet to adopt sustainable practices, owing to lack of awareness about potential technologies, and the considerations for selection. To this end, the current study aims to survey commercial buildings to explore the technologies implemented together with the basis that influenced the implementation. A detailed survey including semi-structured interviews with professionals engaged in the selected non-domestic buildings were conducted. The selected buildings comprise three (3) certified retrofit, eight (8) certified new and seven (7) non-certified green. The findings show that the buildings have incorporated 54 different technologies under the main sustainability criteria of water efficiency, lighting, heating, ventilation, and air conditioning (HVAC) systems, indoor environmental quality, and sustainable site. Advanced technologies, such as free cooling appliances, on-site wastewater treatments, and water-efficient climate-tolerant plantings, were predominantly found in green-certified buildings, while non-certified buildings tend to adopt more universally applicable and accessible technologies, like LED lighting, compact fluorescent lamps, and low-flow plumbing fixtures. The paper presents a detailed analysis on use of technologies with different building function, green rating levels, and challenges faced. Hence, the study findings would facilitate technology adaptation for a given context by providing insights into the availability and adaptability of green retrofit technologies in the Sri Lankan context for non-domestic buildings.

Exploring global accessibility of deep ocean water for sea water air conditioning (SWAC) process: Identifying feasibility areas depending on temperature source

Sea Water Air Conditioning (SWAC) technology is a highly efficient alternative to conventional air conditioning system using renewable marine energy to provide cooling to buildings. However, its implementation requires access to Deep Ocean Water (DOW) at 4–5 °C, thus SWAC is only viable in coastal regions. Furthermore, one of the major obstacles to its global development is the investment cost that remains high. This cost is strongly linked to the bathymetry of the installation location as it determines the length of the drawing pipeline, which accounts for the largest share of the investment cost. Knowing the temperature and bathymetry profiles will enable the establishment of the financial viability of SWAC technology in a specific location. This paper presents an analysis identifying areas of feasibility on a worldwide scale for standard SWAC implementation first. Then, it explores an alternative design with a higher drawing point for seawater at 12 °C (coupled with a High Temperature District Cooling), which reduces the cost by shortening the drawing pipeline and allows for more locations to be suitable for this technology. Additionally, the impact of the El Niño/Southern Oscillation (ENSO) is also considered since a shallower drawing point makes it more sensitive to temperature variations.

Accelerated Water Desorption of Oligomeric Poly(ethylene glycol) by Addition of Poly(propylene glycol) for Energy-Efficient Water Recovery Systems.

Adsorbents are used to recover water vapor from the atmosphere in desiccant air conditioning (DAC) and atmospheric water harvesting (AWH) systems. Solid adsorbents have been conventionally used in these systems, though liquid adsorbents are considered to be more effective for energy-efficient fluidic thermosystems because of their low regeneration temperatures (45-70 °C). While most previous studies have focused on improving the adsorption performance, the desorption performance of adsorbents can also be a critical factor in improving the energy efficiency of these systems. Thus, this study aimed to improve the water desorption efficiency, focusing on the liquid adsorbents. We found that mixing hydrophobic molecules into a liquid adsorbent decreases the desorption temperature and increases the water-desorption efficiency. Oligomeric poly(ethylene glycol) (PEG), a common moisture-adsorbing liquid oligomer used in detergents and cosmetics, was selected as the liquid adsorbent. Oligomeric poly(propylene glycol) (PPG), which has a structure analogous to PEG and lower hygroscopicity, was selected as the hydrophobic molecule. Water adsorption and desorption experiments showed that the mixture of PPG with PEG promoted the desorption of water molecules beyond that of PEG, while thermogravimetric differential thermal analysis revealed a decrease in the water desorption temperature with increasing PPG content. The improved desorption efficiency was ascribed to the likely water adsorption equilibrium between PEG and PPG in the blend; water molecules are preferentially desorbed from PPG, which has weaker water-adsorbate interactions. The proposed concept is expected to be incorporated into various hygroscopic liquids to develop energy-efficient liquid adsorbents for DAC and AWH.

Thermodynamic and economic seasonal analysis of a transcritical CO2 supermarket with HVAC supply through ice thermal energy storage (ITES)

A real case of a supermarket where a CO2 refrigerating plant also supplies heating, air conditioning and hot water is considered. Ice thermal energy storage (ITES) is used both as latent storage in summer and as sensible thermal energy storage (TES) in winter to partially cover the space cooling/heating load of the supermarket. In particular, it allows to reduce peaks in the electrical power use, when the refrigeration and HVAC systems are running at full power together with ovens and heaters for meals. A thermodynamic analysis, including a detailed theoretical model of the formation and melting of ice on the coils, is carried out to predict the behaviour of ITES during the charging and the discharging phases. A daily energy analysis for both a winter and a summer typical day, and an annual analysis are carried out for the whole system. In summer, two cases are evaluated, i.e. supplying the whole AC demand in the morning or partially covering the AC demand to reduce the design capacity of the reversible heat pump. In all cases, the use of ITES aimed at shaving electrical peaks leads to a higher electrical energy use, also on an annual basis. However, the cost analysis reveals significant benefits, including a reduction in the required capacity of the reversible heat pump, better exploitation of tariffs and the avoidance of installing an electrical transformer in a dedicated room. This results in savings €58,699 over 10 years €47,888 over 15 years, making the choice of ITES more economically advantageous within the typical lifetime of these systems.

Preliminary Research on Water Supply, Drainage, and HVAC Equipment in Shanghai Historic Buildings During the Northern Warlord Period

During the Northern Warlord Period (1912–1928), the construction industry in Shanghai underwent robust development. As an integral element of buildings, equipment served both functional purposes and stood witness to the evolution of the economy and society, thus earning its place as part of the architectural heritage. However, due to various reasons, there are many loopholes in the protection of these building equipment. This paper examines the development of building equipment in Shanghai during the Northern Warlord Period, using water supply, drainage, and heating, ventilation, and air conditioning (HVAC) systems as examples. Through historical context analysis, it summarizes this development from a social-spatial perspective, infers the reasons behind it, and analyzes the importance of preserving such equipment, considering both past and present viewpoints. In this research, the importance of protecting historical building equipment is emphasized, which aims to give people a deeper understanding of their cultural value, and suggests that scholars conduct more practical research on their protection.

Retrospective dynamic life cycle assessment of residential heating and cooling systems in four locations in the United States

Heating, ventilation, and air conditioning systems (HVAC) and water heaters are responsible for a relevant portion of the total Greenhouse Gas (GHG) emissions related to the building life cycle. A significant effort will be needed to substantially reduce building-related GHG emissions to meet the increasing demand to meet goals for energy use and GHG emission reduction. This study evaluates the GHG emissions of two alternative residential HVAC systems: natural gas furnace and electric air conditioning, and an electric heat pump, in a typical single-family house located in four different climate zones in the U.S. using a life cycle assessment model that includes spatial variations such as climate and electricity generation mix and temporal variations such as the changes in the generation mix and greenhouse gas emission factors for electricity generation over time. The locations selected are in very cold, cold, marine (temperate), and hot-humid climate zones in the U.S. The reduction in GHG emissions over time occurred due primarily to the changes in the electricity grid mix. As a result, the heat pump system had the greatest reduction in GHG emissions over time and had the lowest GHG emissions over the study period in two of the four locations. If the decarbonization of electricity production continues and refrigerants with low GHG potential are widely used, the heat pump can be the HVAC system with the lowest GHG emissions in all climate zones studied.

Heat Stress as a Barrier to Successful Reproduction and Potential Alleviation Strategies in Cattle.

In recent decades, the adverse effects of global warming on all living beings have been unanimously recognized across the world. A high environmental temperature that increases the respiration and rectal temperature of cattle is called heat stress (HS), and it can affect both male and female reproductive functions. For successful reproduction and fertilization, mature and healthy oocytes are crucial; however, HS reduces the developmental competence of oocytes, which compromises reproduction. HS disturbs the hormonal balance that plays a crucial role in successful reproduction, particularly in reducing the luteinizing hormone and progesterone levels, which leads to severe problems such as poor follicle development with a poor-quality oocyte and problems related to maturity, silent estrus, abnormal or weak embryo development, and pregnancy loss, resulting in a declining reproduction rate and losses for the cattle industry. Lactating cattle are particularly susceptible to HS and, hence, their reproduction rate is substantially reduced. Additionally, bulls are also affected by HS; during summer, semen quality and sperm motility decline, leading to compromised reproduction. In summer, the conception rate is reduced by 20-30% worldwide. Although various techniques, such as the provision of water sprinklers, shade, and air conditioning, are used during summer, these methods are insufficient to recover the normal reproduction rate and, therefore, special attention is needed to improve reproductive efficiency and minimize the detrimental effect of HS on cattle during summer. The application of advanced reproductive technologies such as the production of embryos in vitro, cryopreservation during the hot season, embryo transfer, and timed artificial insemination may minimize the detrimental effects of HS on livestock reproduction and recover the losses in the cattle industry.

Thermodynamic investigation of solar-powered integrated humidification-dehumidification and vapor compression refrigeration system

Throughout the functioning of an air conditioner working on the principle of vapor compression (VCR system), the heat which is taken up by its evaporator, is thrown away by its condenser. The heat rejected by the condenser is frequently wasted, and it actually causes thermal pollution by increasing the temperature of the surrounding air. Aside from this, freshwater shortage is a severe issue in many regions. With the use of the waste heat of VCR system, it is intended to combine the air conditioning and humidification-dehumidification (HDH) water desalination, and to address these problems. The system supplies potable water, cool air, and warm water whilst avoiding the thermal pollution. Though the integration of the cooling and the desalination units has attracted the interest of some scholars, the duct construction in the current work is the new idea. In this study, the required spray water temperature in humidifier is found considering the human comfort inside the cabin. The impacts of ambient conditions, temperature of saline water, and efficiency of the humidifier on output and performance parameters are explored. The thermodynamic model developed in this research is validated by experimental studies. For the provided operating conditions, the gained output ratio (GOR), the cooling performance (CP), the energy performance coefficient (COEP), and the exergetic efficiency are 2.26, 0.70, 1.94, and 18.67%, respectively.

Performance improvement for chilled water air conditioning cooling coils with various dimple fin geometries

The present research inspected the thermal and flow behavior of finned coiled tube heat exchangers in crossflow for chilled water air conditioning systems. The investigation variables cover the impacts of several variables, such as fin dimple shape, the number of fins, and the Reynolds number of water and air sides on the thermal-hydraulic aspects of a finned cooling coiled tube heat exchanger. The goal is to enhance this famous finned cooling coiled tube heat exchanger using dimples concerning the same coiled tube heat exchanger without dimples. Six test specimens were fabricated, three with fin dimple geometries as sharp-sided triangle dimples, curved-sided triangle dimples, and teardrop dimples. The other specimens with three different fin numbers 140, 155, and 170. The test runs were experimented in a transparent air duct with air Reynolds numbers ranging from 1540 to 6205, while the chilled water flow side has experimented with Reynolds numbers ranging from 3350 to 16250. The findings revealed that a higher Nusselt number and flow area goodness factor is achieved by a heat exchanger (D) with a curved-sided triangle fin dimple shape. The energy efficiency ratio for a cooling coil with a fin number of 170 is higher than that of cooling coils with fin numbers 140 and 155 by approximately 24.68% and 12.94%, respectively. Correlations of energy efficiency ratio, effectiveness, flow area goodness factor, and friction factor are extracted according to the experimental results with deviations.

Effect of Facilities Performance and Quality on User’s Satisfaction with Facilities Provided in Industrial Training Fund Building Maitama, Abuja

The study investigated user satisfaction and performance of facilities management service delivery in private high-rise buildings using the industrial training fund (ITF) house Maitama, Abuja, as a study area. Survey research was carried out through the use of a questionnaire instrument. Three hundred fifty questionnaires were administered to users, of which 304 were retrieved. The simple random sampling technique was adopted for the study, while data obtained from the field were analysed using statistical packages for social. The study found that only pest control services, security facilities (e.g. CCTV), parking facilities, and fire extinguishers were rated well by the respondents in the study area. Results also indicate that users were delighted with leisure facilities (e.g. seating bench), refuse disposal facilities, intercom system and TV reception, and recreational facilities and were satisfied too with fire alarms. Users are happy with the pest control systems in the ITF building, security facilities, parking, fire extinguishers, electricity supply systems, water supply systems and air conditioning. Further findings show that facilities performance explains 78.9% of the variance in user satisfaction which is highly significant (Sig. = .000) as indicated by the F-value of 394.4. Furthermore, standardised Beta coefficients indicate that quality has the most significant beta coefficient of 0.826, thus making the most substantial contribution in explaining user satisfaction which means facilities' performance and quality have a positive and significant effect on user satisfaction. The study concluded that ITF building Maitama, Abuja facilities are performing satisfactorily. This suggests that the building owners and operators must put substantial provisions in place to perform satisfactorily. Finally, the study recommended that owners and management of high-rise buildings must recognise the need to improve the effectiveness of Facilities service to make the buildings more functional and comfortable for users.

Evaluation of a novel porous antimicrobial media for industrial and HVAC water biocontrol.

A novel treatment method, consisting of pea-gravel with a marine coating supplemented with alkyldimethylbenzylammonium chloride (ADBAC or benzalkonium chloride), has been examined for its antimicrobial performance and coating stability in aqueous environments. Initial column studies examining the porous media's ability to reduce bacterial loads in heating, ventilation, and air conditioning (HVAC) water found average reductions of 94% from pre-flush levels (106 colony forming unit (CFU)/mL) when assessed with R2A spread plates and 83% reductions with SimPlates. There was no observed statistical difference between the average of pre- and post-flush waters from four tests of the media without ADBAC. Taxonomic identification, by 16S rRNA gene sequencing, of colonies drawn from pre- and post-ABDAC R2A plates showed similarities with taxa observed in high frequency from prior cultivation-independent surveys of other cooling tower systems. With this proof of concept, two versions of the media were evaluated for potential coating components released during aqueous exposure. Neither released measurable volatile organic compounds (VOC) components, but one did release bisphenol A and ABDAC compounds. Subsequent column tests of the more durable coating were conducted using cultures of interest in industrial water and demonstrated significant reductions in neutralized post-column Enterococcus faecalis samples and near complete loss of Legionella pneumophila in non-neutralized fluids, but lower reductions in Pseudomonas aeruginosa.

Energy-saving optimization of air-conditioning water system based on data-driven and improved parallel artificial immune system algorithm

As the air-conditioning water system is designed according to the maximum load, the system will deviate from its optimum state while operating under partial load. Therefore, it is critical that the numerous operating parameters of the various equipments in the system are dynamically adjusted in an effective and timely manner to maximize the operational energy efficiency of the system. To this end, an improved parallel artificial immune system (IPAIS) algorithm is proposed to determine the optimal operating parameters of the system under different loads. Before optimization, the power consumption model is developed using generalized regression neural network (GRNN) combined with mechanism model for each kind of equipment in the system. Afterwards, the optimal control problem is described with the objective of minimizing the total power consumption of all equipments and considering the relevant constraints. Subsequently, the IPAIS is developed to solve the problem by introducing four improvement strategies. Finally, a simulation experiment is conducted using an actual case of an air-conditioning water system. The results show that the developed power consumption model performs well in accuracy, robustness and generalization ability, and the total system energy consumption is reduced by 15.19% after optimization. Meanwhile, the IPAIS is extended to five variants to confirm the functionality and effectiveness of each improved strategy. Furthermore, the optimization performance of IPAIS in the actual system is comprehensively verified and analyzed using an experimental platform. Compared with the comparison algorithms, IPAIS is able to achieve superior optimization results and presents significant advantages in convergence, robustness and computational complexity.