Browse Topic: Defoggers

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A Performance-driven Numerical Approach for Optimizing the Plenum Opening Area of Cowl Box2026-26-0461To be published on 01/16/2026
There is a scarcity of research in literature regarding the determination of Plenum Opening Area of cowl box. The area of the plenum opening in the cowl box significantly affects the airflow rate in fresh airflow modes, such as face and defrost modes, as well as issues related to water ingress. Primarily, the size of the plenum opening is determined by the necessary HVAC airflow rate. This study aims to investigate how the plenum opening area impacts both airflow discharge and the water ingress issue in the HVAC module. A novel approach is introduced in this research to determine the optimal plenum opening area of the cowl box, taking into account both airflow rate and water ingress concerns. The ANSYS FLUENT software is utilized to analyze airflow discharge in both face and defrost modes, while the SPH (Smooth Particle Hydrodynamics) based Preonlab tool is employed for water ingress analysis. Airflow discharge is evaluated for various plenum opening sizes in both modes, and the area
Baskar, Subramaniyan, A Sr, Mahesh, Gopinathan, Nagarajan
Numerical Analysis of Rear Windshield Deicing with Heating Wires2026-26-0373To be published on 01/16/2026
Motivation: Windshield deicing is a crucial safety feature in vehicles, typically associated with the front windshield. However, the rear windshield also plays a significant role in ensuring safety and needs to be clear. Deicing of the front windshield is usually done using the hot air nozzle from the HVAC system. Modern rear windshields are equipped with heating wires that generate heat upon electrical supply to facilitate deicing. However, excessive use of these heating wires can lead to unnecessary energy consumption, impacting the vehicle's overall efficiency. This is the key motivation behind the development of an optimized heating system for the rear windshield. Problem: Design an optimized heating system for rear windshields that balances effective deicing with minimal energy usage, enhancing both safety and energy efficiency in vehicles. Methodology: This paper explores the numerical application of heating methods using CFD software to deice the rear windshield. The study
Kumaravel, Rajarajeshwari, Ibrahim, Sayyaf, Mathew, Ronnie
Simulation Driven Design of HVAC Systems under Competing HVAC Noise and Defrost Performance Requirements2021-01-102008/31/2021
It is particularly easy to get tunnel vision as a domain expert, and focus only on the improvements one could provide in their area of expertise. To make matters worse, many Original Equipment Manufacturers (OEMs) are silo-ed by domain of expertise, unconsciously promoting this single mindedness in design. Unfortunately, the successful and profitable development of a vehicle is dependent on the delicate balance of performance across many domains, involving multiple physics and departments. Taking for instance the design of a Heating, Ventilation & Air Conditioning (HVAC) system, the device’s primary function is to control the climate system in vehicle cabins, and more importantly to make sure that critical areas on the windshield can be defrosted in cold weather conditions within regulation time. With the advent of electric and autonomous vehicles, further importance is now also placed on the energy efficiency of the HVAC, and its noise. During the development of the defrost mode of an
Nagarajan, Vijaisri, Biermann, Jan, Goldberg, Jens, Motiwala, Hamza, Martins, Diogo, Luzzato, Charles, Mukutmoni, Devadatta
Parametric Modelling and Performance Analysis of HVAC Defroster Duct Using Robust Optimization Methodology2020-01-125004/14/2020
Thermal comfort and safety of automotive passengers are the most important factors in the development of the automotive HVAC system. HVAC system is responsible for the demisting and defrosting of the vehicle’s windows and for creating/maintaining a pleasant environment inside the cabin by controlling airflow and temperature. Fog or ice which forms on the windshield is the main reason for invisibility and leads to major safety issue to the customers while driving. It has been shown that proper clear visibility for the windshield could be obtained with a better flow pattern and uniform flow distribution in the defrost mode of the HVAC system and defrost duct. Defroster performance has received significant attention from OEMs to meet the specific global performance standards of FMVSS103 and SAE J902. Therefore, defroster performance is seriously taken into consideration during the design of HVAC system and defroster duct. The HVAC unit provides hot air to the defroster duct which is
Khan, Mohsin, Khan, Mohsin, Valencia, Manuel, Garikipati, Nagababu, Garikipati, Nagababu, Marginean, Calin
Passenger Vehicle Windshield Demisting and Defrosting SystemsJ902_201909 (Current)09/25/2019
This SAE Recommend Practice establishes for passenger cars, light trucks, and multipurpose vehicles with GVW of 4500 kg (10000 pounds) or less, as defined by EPA, and M1 category vehicles as defined by the European Commission:
Interior Climate Control Vehicle OEM Committee
Implementation of Reinforcement Learning on Air Source Heat Pump Defrost Control for Full Electric Vehicles2018-01-119304/03/2018
Air source heat pumps as the heating system for full electric vehicles are drawing more and more attention in recent years. Despite the high energy efficiency, frost accumulation on the heat pump evaporator is one of the major challenges associated with air source heat pumps. The evaporator needs to be actively defrosted periodically and heat pump heating will be interrupted during defrosting process. Proper defrost control is needed to obtain high average heat pump energy efficiency. In this paper, a new method for generating air source heat pump defrost control policy using reinforcement learning is introduced. This model-free method has several advantages. It can automatically generate optimal defrost control policy instead of requiring manually determination of the control policy parameters and logics. More measurement results can be incorporated into the defrost control policy without too many changes in the reinforcement learning algorithm so that the control policy can be better
Zhu, Jingwei, Elbel, Stefan
Effects of the Glass and Body Heat Transfer Characteristics of an Electric Vehicle on its Energy Consumption and Cruising Distance2016-01-026004/05/2016
In order to develop various parts and components of electric vehicles, understanding the effects of their structures and thermal performance on the energy consumption and cruising distance is important. However, such essential and detailed information is generally not always available to suppliers of vehicle parts and components. This paper presents the development of a simple model of the energy consumption by an electric vehicle in order to roughly calculate the cruising performance based only on the published information to give to suppliers, who otherwise cannot obtain the necessary information. The method can calculate the cruising distance within an error of 4% compared to the published information. The effects of the glass and body heat transfer characteristics on the cruising performance in winter were considered as an example application of the proposed model. An anti-fog control method was modeled, where the relative humidity around the front windshield was assumed to be
Ozeki, Yoshiichi, Nagano, Hideaki, Kohri, Itsuhei
Smart Rear Defog2013-01-151004/08/2013
Smart Rear Defog can be defined as an optimized control algorithm that sets the state of a vehicle's rear defog relay based on a logical assessment of vehicle parameters and environmental conditions. The use of the optimized control algorithm will minimize the amount of user interaction needed to operate the rear defogger and it will minimize the amount of heat rejected to the environment which in turn will improve the vehicle's real world fuel economy or electric range. This paper provides a detailed description of the smart rear defog control system as well as evidence to demonstrate its robustness to variances in environmental conditions and vehicle usage compared to the traditional rear defog system commonly used in many vehicles today.
Delorme, Gilles
Effects of Fretting Corrosion on Lift Glass2011-01-143404/12/2011
The electrical architecture design of a rear back glass defrost grid system encompasses many critical criteria that must be integrated into the design. For example, the defrost clip location and interface to the glass must meet all vehicle performance requirements. If the defrost clip to the glass interface is not resistant to vibration and relative movement, detachment and loss of function can occur. This paper describes a back glass defrost clip with a solder joint that is robust to manufacturing variations and customer usage conditions. A designed experiment using Design for Six Sigma methodologies was performed to understand the effects of the attachment interface to the electrical wiring pigtail, and parameters that affect performance. The working constraints, testing set up, validation, and root cause investigation of the clip detachment phenomenon is covered in this paper.
Pyszel, Richard
Commission Regulation (EU) No. 672/2010 of July 27, 2010 Concerning Type-Approval Requirements for Windscreen Defrosting and Demisting Systems of Certain Motor Vehicles and Implementing Regulation (EC) No. 661/2009 of the European Parliament and of the Council Concerning Type-Approval Requirements for the General Safety of Motor Vehicles, their Trailers and Systems, Components and Separate Technical Units Intended therefor.INT-REG-16211/24/2010
Defrosting and Demisting Systems.
Development of an Automatic Windshield Defogging System2009-01-017304/20/2009
The development of an automatic defogging system using an accurate windshield humidity sensor and the existing HVAC hardware is described herein. Improved cabin temperature control and forward visibility for the driver was achieved using a sophisticated automatic defogging strategy integrated into the Automatic Temperature Control microprocessor. Laboratory tests were conducted under various weather conditions and test modes using a climate wind tunnel and field tests were conducted in North America The automatic defogging system worked well in all cases
Kwon, Choon-Gyu, Jang, Ki-Lyong, Lee, Chang-Won, Jung, Seung-Gyoon, Foster, Lee
Development of Next Generation Automatic Climate Control2007-01-118804/16/2007
The majority of today's Automatic Climate Control (ACC) systems are based on linear analog controller technology which was developed in the mid of last century. In cognizance of the state of the ACC technology, we developed a new ACC system based on the concepts of power balance and the separation of transient and steady state control. Production implementations have demonstrated that the new ACC system technology improves overall control performance, and reduces program development time and the associated cost.
Wang, Mingyu, Pawlak, John L., Archibald, Charles A.
Passenger Car Windshield Defrosting SystemsJ902_200307 (Historical)07/09/2003
This SAE Recommended Practice provides a test procedure and performance guideline for evaluating passenger vehicle windshield defrosting systems. It is limited to results of tests that can be conducted on uniform test equipment in commercially available laboratory facilities. The current engineering practice prescribes that for laboratory evaluation of defroster systems, a known quantity of water shall be sprayed on the windshield to form an ice coating and then melted by the defroster under specific vehicle operating conditions. The procedure provides uniform and repeatable laboratory test results, even though under actual conditions such a coating would be removed by scraping before driving the vehicle. The performance obtained, therefore, does not directly relate to actual driving conditions, but serves as a laboratory performance indicator for comparing test results within or between systems. This document is intended as a guide toward standard practice but may be subject to
Interior Climate Control Steering Committee
Investigations of Automotive Defroster and Windshield Flow2001-01-344110/01/2001
The specification of automotive ventilation / defrosting systems has often utilized “trial-and-error” and “prior experience” techniques. But design development and production efficiency has generated a strong interest in using more sophisticated design tools such as computational fluid dynamics. For this purpose a joint experimental and numerical study was undertaken. This comprehensive investigation was divided into two parts. First, the three dimensional defroster flow field was measured using LDA in an actual automobile. Second, LDA and infrared thermography was used to map the flow and temperature fields for a two dimensional jet impinging upon a slanted plate -- a simplified representation of a car defroster geometry.
Becker, Stefan, Lienhart, Hermann, Stoots, Carl, Beier, Max, Hofhaus, Jörn, Schlenz, Dieter, Zemsch, Stefan, Ryssel, Edna
Windshield Defrosting Systems Performance Requirements--Trucks, Buses, and Multipurpose VehiclesJ382_200009 (Current)09/29/2000
This SAE Recommended Practice presents minimum defrosting system performance requirements for trucks, buses, and multipurpose vehicles when tested according to SAE J381. It is the intent that this document will be reviewed and revised to reflect technological progress in vehicle defroster systems.
Truck and Bus Windshield Wipers and Climate Control Comm
Vehicle Defroster System Evaluation2000-01-098403/06/2000
Vehicle defrost systems are required to defrost the windshield and side windows in a short period. This portion of the HVAC system is not only required to work without interfering with operator comfort relating to high temperatures being felt by the drivers face, but also relating to noise. Add to these restrictions the requirement that the defrost outlets used must be esthetically pleasing, and one can see how much development time is required to design an effective defrost system. Once a design is established, it must be tested. The methods currently used to test defrost performance leaves much to be desired, due to the time required to transpose actual test results into usable data. This transposition includes removing marked tracing from the windows in a cold chamber to trace paper, and then the trace paper needs to be reduced into manageable sizes of paper. It is for these reasons that a more cost effective, accurate, consistent, and time efficient method using digital photography
Roberts, Michael B., Moultanovsky, Alexander V., Zeigler, Terry A.
Passenger Car Windshield Defrosting SystemsJ902_199902 (Historical)02/19/1999
This SAE Recommended Practice provides a test procedure and performance guideline for evaluating passenger car windshield defrosting systems. It is limited to results of tests that can be conducted on uniform test equipment in commercially available laboratory facilities. The current engineering practice prescribes that for laboratory evaluation of defroster systems, a known quantity of water shall be sprayed on the windshield to form an ice coating and then melted by the defroster under specific vehicle operating conditions. The procedure provides uniform and repeatable laboratory test results, even though under actual conditions such a coating would be removed by scraping before driving the vehicle. The performance obtained, therefore, does not directly relate to actual driving conditions, but serves as a laboratory performance indicator for comparing test results within or between systems. This document is intended as a guide toward standard practice but may be subject to frequent
Interior Climate Control Steering Committee
Passenger Car Backlight Defogging SystemJ953_199902 (Historical)02/01/1999
The scope of this SAE Recommended Practice is to establish uniform test procedures for passenger cars, to determine whether the system is defined as a defroster or defogger, and to establish minimum performance requirements for each system. A defroster for purposes of this practice is a system which will remove moisture and/or frost from the interior surface of the backlight at -18 °C. A defogger is a system which will remove moisture and/or fog from the interior surface of the backlight at 4 °C. The test procedure is intended to simulate actual conditions by utilizing either a cold room with an appropriate device to introduce air flow over the backlight or a sufficiently large wind tunnel with ambient temperature control. The test procedure and the minimum performance requirements are based on currently available engineering data.
Interior Climate Control Steering Committee
Motor Vehicle Heater Test ProcedureJ638_199811 (Historical)11/05/1998
This SAE Recommended Practice, limited to liquid coolant systems, establishes uniform vehicle heater test procedures. Both laboratory and complete vehicle tests are specified in this document. Required test equipment, facilities, and definitions are included. NOTE—Defrosting and defogging procedures and requirements can be found in SAE J902, J381, J382, and J953.
Interior Climate Control Steering Committee
DAB Multiband Glass Antenna98114402/23/1998
A new type of antenna, installed on the rear glass of a vehicle, to receive both Band III and L band was developed. This antenna consists of a rectangular loop, inductance elements inserted in the loop and a monopole connected to the edge of the loop. It works, through the use of the elements, both as a one-wavelength loop antenna for Band III and a half-wave dipole for L band. This antenna is (1) conformal and (2) compatible with the defogger heater grid lines. As the results of an open site test, this antenna had a higher gain than that of commercially- available whip-type multiband antennas for both bands.
Miyahara, Shunji, Shibata, Naoki
Windshield Defrosting Systems Performance Guidelines--Trucks, Buses, and Multi-Purpose VehiclesJ382_199406 (Historical)06/01/1994
This SAE Recommended Practice presents minimum defrosting system performance requirements for trucks, buses, and multipurpose vehicles when tested according to SAE J381. It is the intent that this document will be reviewed and revised to reflect technological progress in vehicle defroster systems.
Truck and Bus Windshield Wipers and Climate Control Comm
Optimum Design of Defroster Nozzle92016702/01/1992
Time-consuming experiments have heretofore been required for the development of defroster nozzles. To solve this problem, the authors have quantitatively correlated configuration factors for defroster nozzles and air flow distribution through experiments with simplified models and multiple-regression analysis. Using this approach, it has become possible to derive defrosting patterns from defroster nozzle configuration factors in the design phase.
Kohnotou, Takashi, Iwamoto, Yoshiaki, Hoshiawa, Kiyohito, Nagataki, Masanori
Fuel-Fired Heaters-Air Heating-For Construction and Industrial MachineryJ1024_198912 (Historical)12/01/1989
This standard covers off-road, self-propelled work machines as categorized in SAE J1116. This standard outlines requirements that must be met in order for the heating equipment to perform satisfactorily on construction and industrial machinery. This standard describes a general set of parameters covering fuel-fired heaters for heating and defrosting cabs on construction and industrial machinery.
CTTC C4, Cold Weather Operation
Fuel-Fired Heaters - Air Heating - for Construction and Industrial MachineryJ1024_198905 (Historical)05/01/1989
This standard covers off-road, self-propelled work machines as categorized in SAE J1116. This standard outlines requirements that must be met in order for the heating equipment to perform satisfactorily on construction and industrial machinery. This standard describes a general set of parameters covering fuel-fired heaters for heating and defrosting cabs on construction and industrial machinery.
Common Tests Technical Steering Committee
Passenger Car Windshield Demisting and Defrosting SystemsJ902_198410 (Historical)10/01/1984
This SAE Recommended Practice provides a test procedure and performance guideline for evaluating passenger car windshield defrosting systems. It is limited to results of tests that can be conducted on uniform test equipment in commercially available laboratory facilities. The current engineering practice prescribes that for laboratory evaluation of defroster systems, a known quantity of water shall be sprayed on the windshield to form an ice coating and then melted by the defroster under specific vehicle operating conditions. The procedure provides uniform and repeatable laboratory test results, even though under actual conditions such a coating would be removed by scraping before driving the vehicle. The performance obtained, therefore, does not directly relate to actual driving conditions, but serves as a laboratory performance indicator for comparing test results within or between systems. This document is intended as a guide toward standard practice but may be subject to frequent
Interior Climate Control Vehicle OEM Committee
Windshield Defrosting Systems Performance Requirements--Trucks, Buses, and Multipurpose VehiclesJ382_198410 (Historical)10/01/1984
This SAE Recommended Practice presents minimum defrosting system performance requirements for trucks, buses, and multipurpose vehicles when tested according to SAE J381. It is the intent that this document will be reviewed and revised to reflect technological progress in vehicle defroster systems.
Truck and Bus Windshield Wipers and Climate Control Comm
Passenger Car Backlight Defogging SystemJ953_198406 (Historical)06/01/1984
The scope of this SAE Recommended Practice is to establish uniform test procedures for passenger cars, to determine whether the system is defined as a defroster or defogger, and to establish minimum performance requirements for each system. A defroster for purposes of this practice is a system which will remove moisture and/or frost from the interior surface of the backlight at -18 °C. A defogger is a system which will remove moisture and/or fog from the interior surface of the backlight at 4 °C. The test procedure is intended to simulate actual conditions by utilizing either a cold room with an appropriate device to introduce air flow over the backlight or a sufficiently large wind tunnel with ambient temperature control. The test procedure and the minimum performance requirements are based on currently available engineering data.
Interior Climate Control Steering Committee
Motor Vehicle Heater Test ProcedureJ638_198206 (Historical)06/01/1982
This SAE Recommended Practice, limited to liquid coolant systems, establishes uniform vehicle heater test procedures. Both laboratory and complete vehicle tests are specified in this document. Required test equipment, facilities, and definitions are included. NOTE - Defrosting and defogging procedures and requirements can be found in SAE J902, J381, J382, and J953.
Interior Climate Control Steering Committee
Windshield Defrosting Systems Performance Requirements--Trucks, Buses, and Multipurpose VehiclesJ382_197101 (Historical)01/01/1971
This SAE Recommended Practice presents minimum defrosting system performance requirements for trucks, buses, and multipurpose vehicles when tested according to SAE J381. It is the intent that this document will be reviewed and revised to reflect technological progress in vehicle defroster systems.
Truck and Bus Windshield Wipers and Climate Control Comm
Passenger Car Windshield Demisting and Defrosting SystemsJ902A_196706 (Historical)06/01/1967
This SAE Recommend Practice establishes for passenger cars, light trucks, and multipurpose vehicles with GVW of 4500 kg (10 000 lb) or less, as defined by EPA, and M1 category vehicles as defined by the European Commission: a. Minimum performance standards for defrosting and demisting systems. b. Test procedures that can be conducted on uniform test equipment by commercially available laboratory facilities.
Interior Climate Control Vehicle OEM Committee
Passenger Car Windshield Demisting and Defrosting SystemsJ902A_196703 (Historical)03/01/1967
This SAE Recommend Practice establishes for passenger cars, light trucks, and multipurpose vehicles with GVW of 4500 kg (10 000 lb) or less, as defined by EPA, and M1 category vehicles as defined by the European Commission: a. Minimum performance standards for defrosting and demisting systems. b. Test procedures that can be conducted on uniform test equipment by commercially available laboratory facilities.
Interior Climate Control Vehicle OEM Committee
Passenger Car Backlight Defogging SystemJ953_196605 (Historical)05/01/1966
The scope of this SAE Recommended Practice is to establish uniform test procedures for passenger cars, to determine whether the system is defined as a defroster or defogger, and to establish minimum performance requirements for each system. A defroster for purposes of this practice is a system which will remove moisture and/or frost from the interior surface of the backlight at -18 °C. A defogger is a system which will remove moisture and/or fog from the interior surface of the backlight at 4 °C. The test procedure is intended to simulate actual conditions by utilizing either a cold room with an appropriate device to introduce air flow over the backlight or a sufficiently large wind tunnel with ambient temperature control. The test procedure and the minimum performance requirements are based on currently available engineering data.
Interior Climate Control Steering Committee
Passenger Car Windshield Demisting and Defrosting SystemsJ902_196408 (Historical)08/01/1964
This SAE Recommend Practice establishes for passenger cars, light trucks, and multipurpose vehicles with GVW of 4500 kg (10 000 lb) or less, as defined by EPA, and M1 category vehicles as defined by the European Commission: a. Minimum performance standards for defrosting and demisting systems. b. Test procedures that can be conducted on uniform test equipment by commercially available laboratory facilities.
Interior Climate Control Vehicle OEM Committee
PRACTICAL APPROACHES TO COLD WEATHER TESTING58020701/01/1958
The difficulties of outdoor testing for performance of engines, heaters, defrosters, fuel-induction systems and other automotive components are discussed, with illustrations from a typical winter expedition. How these problems are overcome by cold room testing, and practical procedures for reproducing natural problems in the laboratories are outlined. Necessary precautions and specialized equipment are treated with examples from Ford's cold room laboratories.
Runyon, Carl C.
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