Browse Topic: Heating, ventilation, and air conditioning systems (HVAC)
After an investigation into a fruit and vegetable storage compartment on a ship, this paper proposes a method for creating different temperature zones within a single storage unit. To perform this approach, a top perforated plate air supply system should be implemented, and storage panels should act as partitions to make temperature control more accurate in different zones within the same compartment. This method ensures that fruits and vegetables can be stored for the best flavor at suitable temperatures, enabling fewer separate storage units on the ship. According to the experimental results, this solution can preserve various types of fruits and vegetables under different conditions during long trips, deal with the challenge of chilling or freezing injury due to mixed storage, and save the cold storage capacity on the ship. The proposed method has significant value in engineering applications.
The malfunction of the aircraft windshield electric heating system, particularly arc discharge, poses a serious threat to flight safety by causing glass breakage. A systematic study was conducted on the causes and effects of arc faults on windshield structural integrity, employing macroscopic observation, microscopic analysis, and energy dispersive spectroscopy (EDS) following a windshield fracture incident. The results indicate that arc discharge typically occurs at the interface between the heating film busbar and adjacent structures. Localized high temperatures cause the outer glass to fracture, generating radial cracks. The ablation of the busbar silver coating and the carbonization of the PVB interlayer are direct evidence of arc action, whereas the heating wire remains a passive component affected by the high-temperature environment. The fault is primarily attributed to local disbonding at the busbar interface and moisture ingress. Based on the findings, recommendations are proposed for process optimization and inspection method improvement, providing a basis for the safe design and maintenance of windshield structures.
The automotive air-conditioning service ports task force conducted a field survey with MACS (Mobile Air Climate Systems Association) in June 2021. The scope of this survey was to determine the types of failures reported primarily at member service shops related to automotive air-conditioning service ports.
The increasing electrification of vehicles means that heating, ventilation and air conditioning systems have a broader range of tasks and a different priority assessment. In electric cars, air conditioning systems are not only responsible for cooling the passenger compartment, but also for controlling the battery temperature, particularly during rapid charging, which represents a high-load operating point. Furthermore, achieving high thermodynamic efficiency is desirable, as this directly impacts the range of electric cars. The elimination of the combustion engine as a major source of noise prioritizes the noise, vibration and harshness behavior of the refrigerant compressor for product selection. To investigate the vibration and acoustic behavior, as well as the fluid dynamic forces resulting from the cyclic compression principle of an electric refrigerant compressor, a test rig was developed that allows compressors to be operated and measured in isolation in an anechoic chamber under various defined operating conditions. This test rig has been expanded in two ways within the scope of this work. Firstly, the compressor can be either rigidly attached to a dead mass using a VDA mount or measured while suspended freely. Secondly, a new R744-compatible refrigeration circuit has been added to the test rig, enabling compressors operating with the environmentally friendly refrigerant CO₂, which has so far only been used by a few manufacturers in selected models, to be tested. Measurement results obtained using this test rig provide valuable insight into the vibration behavior and sound spectra of the refrigerant compressor's fluid, structural, and airborne noise when operating at different points.
The design, testing, and analysis of a Guided Autorotative Delivery System (GADS) for suppression of incipient wildfires is described. The GADS consists of an unpowered 1 m diameter rotor, a control unit, and a payload of 2.2 kg of fire suppressant powder. On release from a fixed-wing UAV, the rotor passively deploys and enters autorotation, decelerating the payload and allowing precise delivery of the suppressant using cyclic pitch control. A numerical model of the system was developed to calculate the trajectory of the GADS during rotor deployment and descent, in the presence of ambient wind and cyclic pitch inputs. A reduced-scale model of the rotor was tested in a wind tunnel, and an uncontrolled full-scale, 1.5 kg prototype of the GADS was fabricated and tested by dropping from a hovering quadcopter as well as a fixed-wing UAV. The full-scale drop experiments validated the deployment and autorotation stability of the system, and demonstrated that the GADS maintains descent velocities suitable for incipient fire suppression (≈ 5 m/s). Numerical predictions indicate that the GADS descent trajectory can be controlled with cyclic pitch in an ambient crosswind of at least 5 m/s (10 kts). Measurements captured during the drop tests using onboard instrumentation show good qualitative agreement with numerical predictions. Future work will include drop tests with remotely controlled cyclic pitch, followed by fully autonomous controlled descent. The study establishes design guidelines for guided autorotative systems and illustrates their potential for scalable UAV-based wildfire suppression or emergency response.
In the automotive industry, the perceived quality of a vehicle is heavily influenced by the ease and effort required to close its doors (which is governed by total door closing energy), particularly when all windows and other doors are closed. A major contributor to increased door closing energy is the air bind energy, a phenomenon caused by the rapid compression of trapped air within a sealed vehicle cabin during door closure. Studies have shown that this transient event leads to a significant rise in cabin pressure. This study presents a Computational Fluid Dynamics (CFD) method to evaluate the impact of air bind energy on door closing during the early stages of vehicle design. By simulating the cabin pressure dynamics during door closure, the research identifies key parameters influencing the air bind energy, such as door closing velocity, pressure relief valve and airflow escape paths. Other mechanical factors like hinge friction, check arm, and door seal etc. are excluded from the CFD model due to their complexity in simulation. The proposed CFD method is validated using three different vehicle models with varying door closing speeds. Cabin pressure vs time results are compared against physical tests conducted with the EZ-Slam measurement device. The strong correlation between CFD results and physical test data confirms the robustness of this method. Research findings highlight that optimizing the placement & size of pressure relief valve can significantly reduce the air bind energy, thereby lowering the total door closing energy. This is achieved by reducing cabin peak pressure and maximizing the rate at which peak pressure reaches atmospheric conditions. These insights are valuable for automotive engineers, to improve customer satisfaction through reduced door closing effort.
Climate control systems in Battery Electric Vehicles (BEVs), Plug-in Hybrid Electric Vehicles (PHEVs), and Extended Range Electric Vehicles (EREVs) rely on electrical energy to provide cabin heating. In winter conditions, the absence of waste heat from internal combustion engines necessitates increased energy consumption for thermal comfort, which directly impacts vehicle range. Conventional HVAC systems typically operate with a mixture of cold ambient air and recirculated cabin air. However, the proportion of recirculated air is limited due to windshield fogging risks, constraining energy-saving potential. To address this, MAHLE has developed the MAHLE HeatX Range+ that utilizes the thermal energy of exhaust cabin air, that would normally leave the passenger compartment through vehicle body vents, to precondition incoming fresh air, thereby reducing the heating load. This solution is engineered for scalable integration into existing HVAC architectures, allowing adaptation to varying vehicle packaging constraints and performance requirements. The concept is compatible with both direct and indirect refrigerant systems, including R1234yf, R744 and R290 ensuring broad applicability across future vehicle platforms. Experimental validation has been conducted at component, module and vehicle levels. Results confirm substantial heat recovery potential, leading to measurable reductions in HVAC energy demand and corresponding increases in driving range. This measure contributes to improved thermal efficiency and supports the broader objectives of sustainable mobility by enhancing energy utilization and passenger comfort in electrified vehicles.
Electric Vehicles (EVs) are rapidly transforming the automotive landscape, offering a cleaner and more sustainable alternative to internal combustion engine vehicles. As EV adoption grows, optimizing energy consumption becomes critical to enhancing vehicle efficiency and extending driving range. One of the most significant auxiliary loads in EVs is the climate control system, commonly referred to as HVAC (Heating, Ventilation, and Air Conditioning). HVAC systems can consume a substantial portion of the battery's energy—especially under extreme weather conditions—leading to a noticeable reduction in vehicle range. This energy demand poses a challenge for EV manufacturers and users alike, as range anxiety remains a key barrier to widespread EV acceptance. Consequently, developing intelligent climate control strategies is essential to minimize HVAC power consumption without compromising passenger comfort. These strategies may include predictive thermal management, cabin pre-conditioning, zonal climate control, and integration with renewable energy sources. By implementing such energy-efficient solutions, EVs can achieve better range performance, improved user satisfaction, and greater environmental benefits. Modern EV climate control systems increasingly rely on intelligent features such as Auto mode, which dynamically adjusts fan speed, airflow direction, and temperature settings based on real-time cabin and ambient conditions. By leveraging sensor data and adaptive control algorithms, Auto mode optimizes thermal comfort while minimizing unnecessary energy expenditure. This automated regulation plays a crucial role in reducing HVAC-related power consumption, thereby contributing to overall range improvement and enhancing system efficiency without compromising passenger comfort. This study focuses on the development of three distinct Auto mode calibration levels for each set condition, designed to achieve the same cabin temperature with varying dynamic responses and energy consumption profiles. In Auto mode, the cabin temperature is regulated through intelligent control of compressor speed, blower speed, and evaporator temperature. While all Auto levels can maintain the desired setpoint, the time required to reach this temperature and the system’s responsiveness to sudden thermal loads can vary significantly. This study introduces three distinct calibration profiles, each engineered to achieve the same cabin temperature under different dynamic conditions and energy consumption levels. These profiles allow users to choose between faster thermal response or reduced power usage, effectively enabling a trade-off between immediate comfort and extended driving range
The integration of Advanced Driver Assistance Systems (ADAS) into modern vehicles necessitates innovative solutions for interior packaging that balance out safety, performance, and ergonomic considerations. This paper introduces an inverted U-shaped steel tube cross car beam (CCB) as a superior alternative to traditional straight tube designs, tailored for premium vehicle instrument panels. The U-shaped geometry overcomes the limitations of straight tube beams by creating additional packaging space for components such as AR-HUDs, steering columns, HVAC systems, and electronic control units (ECUs). This geometry supports efficient crunch packaging while accommodating ergonomic requirements like H-point, eyeball trajectory, and cockpit depth for optimal ADAS component placement. The vertical alignment of the steering column within the U-shaped design further enhances space utilization and structural integrity. This study demonstrates that the inverted U-shaped CCB is a transformative solution for ADAS packaging, providing superior durability, crash performance, and knee injury mitigation compared to traditional straight tube designs. By addressing challenges such as crunch packaging, structural stiffness, and manufacturing efficiency, the U-shaped beam sets a new standard for global automotive platforms. The findings underscore its potential to revolutionize vehicle interiors, enabling advanced technology integration while maintaining safety and efficiency.
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