Hybrid Cooling System Research Articles

Numerical investigation of high temperature heat pump integrated hybrid cooling system

Over 67 % of the energy demand within the pharmaceutical and semiconductor industries is for their cleanrooms, driven by stringent temperature and humidity control requirements. Despite high energy usage, heating, ventilation, and air-conditioning (HVAC) units consisting of conventional vapor compression systems (CVCS) are favoured for their simplicity. Hybrid cooling systems (HCS) offer potential efficiency gains by separating latent and sensible loads. Still, reliance on fossil-fuel-fired or electric heaters to regenerate the desiccant makes it energy intensive and reduces CO2 mitigation benefits. This study explores high-temperature heat pumps to simultaneously cool process air and heat regeneration air, thereby using multiple benefits. Heat pumps with condensing temperatures of 80 °C, 90 °C, and 120 °C and an ejector-enhanced trans-critical CO2 heat pump were compared with CVCS and HCS. The 120-bu and CO2HP configurations demonstrated a system COP of 2.94 and 3.22, respectively, surpassing CVCS, which has a system COP of 1.44. These setups achieved CO2 emission reduction of 51 % and 55.2 %, compared to CVCS, respectively.

Improved Design and Economic Estimation of Cold-End Systems for Inland Nuclear Power Plants

Improved Design and Economic Estimation of Cold-End Systems for Inland Nuclear Power Plants

Optimization of Hybrid Cooling Systems for Automotive Engines: Integrating Radiator and Air Conditioning Efficiency for Enhanced Performance and Energy Efficiency

Abstract: This research paper introduces a groundbreaking exploration into the optimization of hybrid cooling systems within automotive thermal management. The study focuses on seamlessly integrating radiator and air conditioning components to not only enhance engine performance but also achieve unprecedented levels of energy efficiency. In response to the escalating demand for environmentally conscious and fuel-efficient vehicles, the research delves into advanced engineering solutions and innovative technologies that synergize the functions of traditional radiator and air conditioning systems. The core objective is to harmonize these components, redefining the landscape of automotive thermal management and setting the stage for a sustainable and high-performance future. By scrutinizing advancements, addressing challenges, and proposing potential breakthroughs, the paper contributes to the ongoing discourse on the evolution of engine cooling systems. The findings aim to propel the automotive industry toward a new era where optimal engine performance coexists with energy efficiency and environmental responsibility. This research lays the foundation for future developments that promise to reshape the automotive thermal management landscape, aligning with the global shift towards more sustainable and technologically advanced transportation solutions.

Review on Performance Analysis of Desiccant-Assisted Hybrid Cooling Systems

Due to the growing expense of fossil fuels and other environmental issues, it is crucial to reduce the energy cost of built environment cooling systems without sacrificing indoor air quality and comfort levels. One option in this area is solid desiccant dehumidification-assisted cooling systems, which employ alternative energy sources like solar and biomass and are also environmentally beneficial by the minimal requirement of refrigerants. The present review discusses the performance analysis of different solid desiccants readily accessible on the market and their composites. Better moisture absorption and a lower regeneration temperature are qualities of a better desiccant. The review also discusses the various solid desiccant dehumidifier designs, their benefits, and their disadvantages. Solid desiccant dehumidifiers now come in various combinations, considerably enhancing system performance. The exergy efficiency of desiccant-integrated evaporative cooling is up to 21.5%, comparable with another HVAC system. A summary of the performance parameters has also been created to assess system performance further. This study will benefit innovation and advancement in solid desiccant materials in the air conditioning market.

Energy and Comfort Evaluation of Fresh Air-Based Hybrid Cooling System in Hot and Humid Climates

Maintaining mechanical ventilation has been identified as a potential strategy for reducing the risk of virus infections. However, in hot and humid climatic conditions, delivering fresh air to a building comes at an energy cost and could impact occupant comfort due to the persistent need for simultaneous cooling and dehumidification. In this paper, the performance of a novel hybrid air conditioning system that handles fresh air is studied. In this system, dehumidification is accomplished by a solid desiccant dehumidifier coupled with a cooling coil integrated with the cooling tower of an existing chiller system. Using the data available from an operational desiccant cooling system, a system-level model has been developed and validated to study the potential application of the system in hot and humid climates. The study found that such a system is effective in delivering sensible cooling in all types of climates; thanks to the two-stage cooling in cooling coil and chilled water coils, respectively. However, the system is effective in delivering thermal comfort in regions where the climate has a relatively moderate ambient humidity. For the tropical cities of Darwin, Kuala Lumpur and Bangkok, the system can provide comfortable temperatures, but faces challenges in keeping the humidity within the comfort zone. The system electrical coefficient of performance (COP) is higher than that of refrigerative systems. This system also has the benefit over the refrigerative system of the supply air, which is entirely fresh ambient air and is expected to improve the indoor environmental quality largely.

Experimental Assessment of Rotary Solid Desiccant Dehumidifier Assisted Hybrid Cooling System

"The prime objective of the present investigation is to assess the performance evaluation of rotary solid desiccant dehumidifier integrated vapor-compression integrated hybrid thermally cooling system by experimental investigation for the transient humid conditions. The experimental test set up is precisely designed and practically fabricated so as to obtain the consistent experimental data during performance testing. The main aim of the experimental investigation is to measure the overall system performance of the rotary solid desiccant assisted hybrid dehumidification and cooling system in terms of COP by measurement at various ambient conditions, air stream flow rates and different regeneration temperatures. The desiccant integrated hybrid thermally cooling system (DAHCS) is primarily the environmental protection technique for indoor comfort cooling purpose of the various residential and commercial building applications. This system also reduces the CFC level in the environment because it minimizes the use of conventional refrigerant. It is found that the rotary solid desiccant dehumidifier assisted hybrid cooling system (DAHCS) is alternate suitable option against vapor compression integrated conventional cooling system in transient humid climates. The desiccant assisted hybrid cooling system (DAHCS) has proven their feasibility and energy saving in the field of built environment. It is concluded that this innovative cooling technology is feasible and demand low energy for comfort cooling. This study is very useful in enhancing opportunities to extend further innovation and core research in different areas of desiccant integrated hybrid thermally cooling system.

Performance improvement of solar PV module through hybrid cooling system with thermoelectric coolers and phase change material

This work aims to substantiate the relationship between efficiency of solar modules and the effect of thermoelectric in cooling solar modules in combination (series) with the phase changing material (PCM). Thermoelectric effect is attributed to the “Peltier effect,” and cooling effect of PCM can be attributed to “latent” energy storage. This article focuses on designing a hybrid cooling technique that combines the effect of these two methods to improve solar cell performance, based on the fact that electrical efficiency of solar panels decreases with an increase in module temperature. Using COMSOL Multiphysics software, a simulation study is carried out for different casing materials and PCMs to reach the best combination of Vaseline as PCM and Silver as the back casing, showing the highest increment in panel efficiency of 9.7%. An experimental study is conducted to compare different cooling techniques involving TECs and PCMs. TECs provide better cooling than PCMs under similar conditions as panel efficiency increases by 5.73%. When combined with the finning effect (using copper tubes), PCM is more effective in increasing panel efficiency by 4.27% compared to 3.26% when PCM is added to the casing. Accordingly, an innovative Hybrid Cooling Technique is designed in which the combined cooling effects of TECs, PCMs, and Aluminium Heat Sinks are tested. It is observed that electrical efficiency and panel efficiency show a maximum increment of 19.4% and 19.32%, respectively, with Hybrid Cooling System. Hence, this combination of Peltier effect and latent energy storage provides enhanced cooling to improve solar module performance.

Thermodynamic Study of Solar-Assisted Hybrid Cooling Systems with Consideration of Duration in Heat-Driven Processes

Solar-assisted hybrid cooling systems are promising for the energy saving of refrigeration systems. In most cases, the solar thermal gain is only able to power the heat-driven process of facilities during part of the working period. Therefore, the reduction of compressor power strongly depends upon the duration of heat-driven processes, which has not been addressed properly. Motivated by such a knowledge gap, the thermodynamic understanding of solar-assisted hybrid cooling systems is deepened through considering the duration in heat-driven processes. Three absorption–compression-integrated cooling cycles were taken as examples. It was found that optimal parameters, e.g., inter-stage pressure and temperature, corresponding to various performance indicators tend to be identical, as the duration of heat-driven processes is taken into account. Furthermore, the optimal parameter for different working conditions was obtained. The dimensionless optimal intermediate temperature of layout with the cascade condensation process varies slightly, e.g., 4%, for different conditions. Moreover, the fall of compressor power in the entire working period was nearly independent upon the intermediate temperature. The paper is favorable for the efficient design and operation of solar-assisted hybrid cooling systems.

Gas Turbine Intake Air Hybrid Cooling Systems and a New Approach to Their Rational Designing

Gas turbine intake air cooling (TIAC) by exhaust gas heat recovery chillers is a general trend to improve turbine fuel efficiency at increased ambient temperatures. The high efficiency absorption lithium–bromide chillers of a simple cycle are the most widely used, but they are unable to cool inlet air lower than 15 °C. A two-stage hybrid absorption–ejector chillers were developed with absorption chiller as a high temperature stage and ejector chiller as a low temperature stage to subcool air from 15 °C to 10 °C and lower. A novel trend in TIAC by two-stage air cooling in hybrid chillers has been substantiated to provide about 50% higher annual fuel saving in temperate climate as compared with absorption cooling. A new approach to reduce practically twice design cooling capacity of absorption chiller due to its rational distribution with accumulating excessive refrigeration energy at decreased thermal loads to cover the picked demands and advanced design methodology based on it was proposed. The method behind this is issued from comparing a behavior of the characteristic curves of refrigeration energy required for TIAC with its available values according to various design cooling capacities to cover daily fluctuation of thermal loads at reduced by 15 to 20% design cooling capacity and practically maximum annual fuel reduction.

Energy and Comfort Evaluation of a Fresh Air-Based Hybrid Cooling Systems in Hot and Humid Climates

Energy and Comfort Evaluation of a Fresh Air-Based Hybrid Cooling Systems in Hot and Humid Climates

Development and Assessment of a Novel Air/Water Hybrid Cooling System Coupling Two Units for Energy and Water Saving

Development and Assessment of a Novel Air/Water Hybrid Cooling System Coupling Two Units for Energy and Water Saving

Thermal Comfort and Energy Analysis of a Hybrid Cooling System by Coupling Natural Ventilation with Radiant and Indirect Evaporative Cooling

A hybrid cooling system which combines natural ventilation with a radiant cooling system for a hot and humid climate was studied. Indirect evaporative cooling was used to produce chilled water at temperatures slightly higher than the dew point. With this hybrid system, the condensation issue on the panel surface of a chilled ceiling was overcome. A computational fluid dynamics (CFD) model was employed to determine the cooling load and the parameters required for thermal comfort analysis for this hybrid system in an office-sized, well-insulated test room. Upon closer investigation, it was found that the thermal comfort by the hybrid system was acceptable only in limited outdoor conditions. Therefore, the hybrid system with a secondary fresh air supply system was suggested. Furthermore, the energy consumptions of conventional all-air, radiant cooling, and hybrid systems including the secondary air supply system were compared under similar thermal comfort conditions. The predicted results indicated that the hybrid system saves up to 77% and 61% of primary energy when compared with all-air and radiant cooling systems, respectively, while maintaining similar thermal comfort.

Influence of Operation Schemes on the Performance of the Natural Draft Hybrid Cooling System for Thermal Power Generation

For thermal power generation, the natural draft hybrid cooling system (NDHCs) with airflows in parallel design gives a multi-objective solution for water saving, performance enhancement and maintenance issues, like corrosion, by switching the loads of wet and dry sections. Performances of dry and wet sections interact with each other in the highly integrated system, increasing the complexity of operation strategies. In this context the present paper examines eight different operation schemes to reveal the relationships of ambient conditions and operation schemes. Comprehensive comparisons in the view of cooling efficiency with a same water inlet temperature are conducted firstly. Results show that there exists energy-saving potentials of the water evaporated rate, cooling performances and the pump power for different schemes. Based on the practical boundary conditions, including those of weather data, operation hours and market factors, optimal operation strategies of hybrid cooling are designed to minimize the operation costs of the energy system. For the 660 MW power generating unit integrated with a natural draft dry cooling system (NDDCs), operation costs based on NDHC after optimization decreased about 0.8% in 2010 and 0.35% in 2018 compared with that of the basic system. When comparing with the designed operation modes of hybrid cooling, 0.07 million dollars is saved after optimization.

Experimental Assessment of a Pilot Scale Hybrid Cooling System for Water Consumption Reduction in CSP Plants

Experimental Assessment of a Pilot Scale Hybrid Cooling System for Water Consumption Reduction in CSP Plants

Development of a Hybrid Cooling, Heating, and Power System for Distributed Energy Applications

Abstract A unique hybrid cooling, heating, and power (HCHP) concept has been recently developed as an alternative to environmental control units. It combines a small-scale organic Rankine cycle (ORC) with a vapor compression cycle. The unique drive-train design flexibly and efficiently converts engine waste heat into useful energy in the form of cooling, heating, and power depending upon the energy needs. Compared to a standard military environmental control unit which puts an electric load on a diesel generator, the HCHP system uses engine exhaust heat as the primary energy input. Utilizing the exhaust heat can potentially provide 27% reduction on fuel consumption when operating in the cooling mode. When cooling is not needed, it is able to provide power and/or heating output using engine waste heat—a significant advantage over other heat activated cooling technologies. The prototype unit based on the HCHP design has been developed to demonstrate the concept. It leveraged the microchannel heat exchanger and scroll expander technologies to achieve high-performance, small-size, and low-cost design in order to meet the growing distributed energy applications.

Thermodynamic and exergy analysis of a S-CO2 Brayton cycle with various of cooling modes

The thermal performance of S-CO2 Brayton cycle is deeply affected by the cooling mode as well as the meteorological and hydrologic conditions. We proposed the three different cooling modes, wet cooling system (WCS), dry cooling system (DCS) and hybrid cooling system (HCS), to the S-CO2 Brayton cycle, and its thermodynamic model was established adopting Ebsilon code. From the viewpoints of both energy and exergy, the efficiencies of cycles with WCS, DCS and HCS as well as the exergy loss distribution of component were analyzed, under full and partial load conditions. Then the influences of changeable meteorological parameters on the cycle performance and the corresponding thermodynamic parameters were studied. Results show the generation efficiency of cycle with DCS is highest, followed by that of cycle with HCS and WCS, and the corresponding supply efficiency of cycle with the three cooling modes are in reverse order. The thermal performance of S-CO2 Brayton cycle gradually deteriorates, as the ambient temperature increases (WCS, HCS, and DCS) or relative humidity decreases (WCS and HCS). HCS shows excellent water saving capacity (variation range of water saving ratio is 59.08%~95.56%), and its water saving effect is more obvious, as ambient temperature decreases and relative humidity increases. Meanwhile, HCS brings equivalent cycle thermal efficiency to WCS, which is recommended for the S-CO2 Brayton cycle in the water arid regions. The present research may lay a foundation for the water cooling system design and the whole cycle operation optimization.

Thermodynamic Performance and Water Consumption of Hybrid Cooling System Configurations for Concentrated Solar Power Plants

The use of wet cooling in Concentrated Solar Power (CSP) plants tends to be an unfavourable option in regions where water is scarce due to the high water requirements of the method. Dry-cooling systems allow a water consumption reduction of up to 80% but at the expense of lower electricity production. A hybrid cooling system (the combination of dry and wet cooling) offers the advantages of each process in terms of lower water consumption and higher electricity production. A model of a CSP plant which integrates a hybrid cooling system has been implemented in Thermoflex software. The water consumption and the net power generation have been evaluated for different configurations of the hybrid cooling system: series, parallel, series-parallel and parallel-series. It was found that the most favourable configuration in terms of water saving was series-parallel, in which a water reduction of up to 50% is possible compared to the only-wet cooling option, whereas an increase of 2.5% in the power generation is possible compared to the only-dry cooling option. The parallel configuration was the best in terms of power generation with an increase of 3.2% when compared with the only-dry cooling option, and a reduction of 30% water consumption compared to the only-wet cooling option.

Performance of Solar Absorption-Subcooled Compression Hybrid Cooling System for Different Flow Rates of Hot Water

The solar absorption-subcooled compression hybrid cooling system (SASCHCS) is tech-economically feasible for high-rise buildings. Since such a system operates with no auxiliary heat source, the performance coupling of its absorption subsystem and solar collectors is sensitive to the variation of hot water flow rate. In this regard, the relationship of system performance and hot water flow rate is required to be clarified exactly. Therefore, this paper aims to illustrate the effect mechanism of hot water flow rate and to propose the corresponding decision criterion. The case study is based on a typical high-rise office building in subtropical Guangzhou. The daily working process of this system with different hot water flow rates is simulated and analyzed. Subsequently, the useful heat of collectors and cooling capacity of the absorption subsystem with the hot water flow rate is discussed in detail. The results show that the SASCHCS operates with hot water temperatures ranging from 60 °C to 90 °C. The energy saving increases with the rise of hot water flow rate, but such variation tends to be flat for the excessively high flow rate. As the collector flow rate increases from 1 m3/h to 10 m3/h, the daily energy saving improves by 21% in August. Similarly, the daily energy saving increases by 37.5% as generator hot water flow rate increases from 1 m3/h to 10 m3/h. In addition, the collector flow rate of 3.6 m3/h (13.33 (kg/m2 h)) and the generator flow rate of 5.2 m3/h (19.26 (kg/m2 h)) are optimal for the annual operation, with considering power consumption of water pumps. This paper is helpful for the improvement of SASCHCS operating performance.

Effect of Hot Water Setting Temperature on Performance of Solar Absorption-Subcooled Compression Hybrid Cooling Systems

The solar absorption-subcooled compression hybrid cooling system (SASCHCS) displays outstanding advantages in high-rise buildings. Since the performance coupling of collectors and absorption subsystems is stronger due to the absence of backup heat and the effect of generator setting temperature has not been realized adequately, it is highly important to study the relationship of SASCHCS operation and the set point temperature of hot water to prevent performance deterioration by inappropriate settings. Therefore, the paper mainly deals with the effect of collector and generator setting temperature. The investigation was based on the entire cooling period of a typical high-rise office building in subtropical Guangzhou. The off-design model of hybrid systems was built at first. Subsequently, the impact mechanism of setting temperature in two hot water cycles on facility operation was analyzed. It was found that the excessive rise of collector setting temperature deteriorated the energy saving, while the appropriate improvement of generator set point temperature was beneficial for the solar cooling. Besides, global optimization by the genetic algorithm displayed that 71.6 °C for the collector setting temperature with 64.5 °C for the generator was optimal for annual operation. The paper is helpful in enhancing the operation performance of SASCHCS.

Design, Build, and Test a Hybrid Cooling System for Crash Helmet

In this current work, a designed hybrid cooling system is proposed which combines a phase change material (PCM) aimed to absorb the excess heat from the user’s head and thermoelectric technology (TEC) amid to cool the PCM in order to compensate the cold temperature lost when cooling the users head. This combination solved a major problem found in previous research studies, the limited usage time for the PCM pouch. The simulation in stand-still condition predicted a heatsink temperature of about 80 °C and a cooling temperature for the head around 24 °C. For moving conditions, the heat sink temperature reached 50 °C and the cooling temperature for the head reached 24 °C. The simulation showed the need of cooling the heat sink to obtain maximum performance. Experimentally, the system has been built and it was guided by the predictions, and tested with an infrared (IR) camera. Testing outcomes showed good results and no overheating in any part of the system by recording a temperature of 25 °C for the heat sink in stand-still condition and 19.5 °C in moving conditions as designed. Therefore, it can be concluded that the designed system has worked successfully and improves the comfortability while wearing a crash helmet.