Heat Fan Research Articles

Pre-weaning heat stress alters liver transcriptome and DNA methylation in dairy calves.

Prenatal hyperthermia has long-lasting impacts on dairy calf metabolism, immunity, and productivity. Yet, the effects of postnatal heat stress on neonatal calves remain unclear. As such, this study aimed to investigate the impact of heat stress on the pre-weaned dairy calf liver gene expression and DNA methylation profiles. Holstein dairy calves were exposed to summer heat stress (daily average THI >78) for 42 d postnatally (i.e., birth to weaning) with access to active fan heat abatement (postnatal cooling, post-CL; calf-height air speed 2.05 m/s, n = 12) or not (postnatal heat stress, post-HS; calf-height air speed 0.15 m/s, n = 12). All thermoregulatory responses were lower in post-CL relative to post-HS calves throughout the experimental period (-12 bpm, -2.5°C, and -0.11°C for respiratory frequency, rectal temperature, and ear skin temperature, respectively). Liver tissue was harvested via biopsy (n = 6 male calves per treatment) at 42 d of age for RNA sequencing and reduced representation bisulfite sequencing. There were 73 differentially expressed genes (DEG), of which 31 were downregulated and 42 were upregulated in post-HS relative to post-CL treatments (FDR cut-off 20%). Ingenuity Pathway Analysis revealed that postnatal heat stress significantly impacted 24 pathways and 60 transcription regulators, including pathway PI3K/AKT, and transcription regulators PPARGC1A, STAT5B, CREB, and X-box binding protein. A total of 14,639 differentially methylated cytosines (DMC) were found across the entire bovine genome; these DMCs mapped to 3,197 differentially methylated genes (DMG), with about 300 DMGs with DMCs located close to the transcription start site. These DMGs are closely related to metabolic pathways, such as PKA, AMPK, MAPK, and STAT3 signaling. Overall, pre-weaning exposure of dairy calves to heat stress changes hepatic methylation profiles, which in turn may impact the expression of genes with critical roles in intracellular signaling and development, metabolic, and immune-related pathways. Providing mechanical cooling via fans to dairy calves in summer seems beneficial to promoting thermoregulation and liver cellular hemostasis.

Induction heating simulation for aircraft RTM toolings

Aircraft CFRP parts as sharklets are produced in resin transfer molding (RTM) tooling. The parts need to be heated up homogenously over the whole area with a constant temperature. The complex shape and accessibility of the tooling make it hard to introduce a common heating system. In addition, the heat must be transferred through the Invar metal tooling structure onto the CFRP. Infrared lamp, air fan and microwave heating are concepts in development. Electrical heating layer mats and cages are laborious in applying. Induction has the advantage of contact-less, efficient, and fast heating. Induction heating was tested for the structural bonding of CFRP frames and stringers showing high bonding strengths. To apply this technology for the RTM tooling, the placement and distance of the induction coils is important. Simulation can help to find the right adjustments and power needed for induction heating. With the program COMSOL the surface and the coils are modeled, and the numerically structured net is divided in small tetrahedron and quadratic sub elements. Since there is no magnetic streamline in the middle of the coil-section, a symmetric halving of the structure is applied as a boundary condition. The temperature-time development and the distance of the coils are simulated in 2D and 3D. Due to the material properties of the magnetic flux concentrator (MFC), higher flux concentration of the magnetic field occurred only in 2D. The results are validated by experiments and are in good agreement.

The Performance Comparison of Multiloop PID Controller on NCS Temperature Plant Based on UDP and TCP

Hardware implementations of networked control systems (NCS) are still rarely found in various research publications so that technical issues, such as how to measure random delay and substitute it into the control equation, still need to be studied further. This study is therefore aimed to compare the performance of NCS based on the used protocol in the ethernet network, i.e. user datagram protocol (UDP) or transmission control protocol (TCP), by applying it in room temperature plant. In this study, the controlled plant is influenced by the fan speed, heating, and window position plant. The heating plant is employed as the main control, while the others are set as sub-plants. The three plants use proportional–integral–derivative (PID) controller where they are regulated by fuzzy logic as the master control unit (MCU). The MCU and three PID controllers are located in the master terminal unit (MTU) while the actuators and sensors are located in the three different remote terminal units (RTU). The verification experiment shows that there is no overshoot on TCP-based NCS, while UDP has 0.725%. For the risetime, the response on UDP is faster than TCP (110.22 as compared to 138.18 s). The same thing also happened to the settling time, where the time with UDP was 101.86 s and 128.44 s for TCP.

Energy modelling and analysis of variable speed series fan-powered terminal units (FPTUs) using energy management system (EMS) in EnergyPlus

The energy impact of constant and variable speed fan operations in series fan-powered terminal units (FPTUs) was investigated by simulating a small office building with four climates in EnergyPlus. While the existing module in EnergyPlus was used to model the performance of constant speed FPTUs, the performance model of variable speed FPTUs was implemented by using energy management system and user-defined modules. Compared with constant speed FPTUs, the variable speed FPTUs could save up to 90% of terminal unit fan energy, 4% of central supply fan energy, and 6% of central cooling coil energy although the heating energy increased due to reduction of fan motor heat gains. The overall savings in the HVAC system was in a range of 15–35% depending on local climates. The demonstration of modelling variable speed series FPTUs in EnergyPlus could increase the awareness of energy efficiency design and promote its incorporation into standard EnergyPlus modules.

Comparison of Heat Treatments by Floor Heating and Fan Heating for Bed Bug Control

Background: Non-chemical methods are as important as pesticides to control bed bugs. The most effective method is heat treatment. Underfloor heating is widely used in residential buildings in Korea, and the benefits of floor heating can be utilized in heat treatment for bed bug control.Methods: Simulations of indoor air flow and heat transfer were performed to compare and analyze the temperature distributions with different heating methods for bed bug control using floor heating and fan heater methods.Results: Even though the average indoor temperature of floor heating was lower, it was more uniform with floor heating than that of fan heating under the assumed conditions. Local cold spots disappeared with the floor heating method.Conclusions: It was confirmed that floor heating has advantages over fan heating to achive uniform high temperatures during heat treatment for exterminating bed bugs.

Automatic shoe drying oven integrated with Raspberry Pi Cloud system for advanced footwear industry

The drying oven functions to reduce the moisture content of raw materials until it reaches a certain moisture content to slow the rate of product damage due to biological and chemical activity. This research aims to design an automatic shoe-drying oven equipped with an LCD screen, exhaust fan, 8-level shelf, and electric heating temperature controller to provide maximum and even heating of leather shoes when gluing and drying leather shoes. Raspberry PI aims to combine and collect production process data in cloud storage in the form of a database, which will then be sent and displayed directly to the operator. The research methodology includes design, manufacturing, assembly, operational testing, performance testing, and evaluation stages. It can be concluded that the research results and progress reports include: (1) The design of the work system and mechanical system for the shoe drying oven can work well. (2) The Raspberry PI Cloud system can collect and display actual drying time data, (3) glue drying temperature of 60°C with a drying time of ±5 minutes, (4) skin heating temperature (texture creation) of 50°C-55°C requires warm-up time ±40 minutes, (5) This machine requires 850 watts of power.

Equipment noise evaluation based on auditory saliency map

This study focuses on noise evaluation and targeted noise reduction efforts. Goals of this study are to propose a noise annoyance evaluation (D) by developing the auditory saliency model. D replaces complex subjective measurements with concrete objective values. This noise evaluation method improves the accuracy of sound quality evaluation by avoiding the bias caused by different emphasis in traditional noise evaluation schemes and the huge workload caused by using questionnaires. Whether it is equipment operation noise or environmental noise, analyzing the noise frequency structure is an important part of achieving targeted noise reduction. Through the EA model (Early Acoustic Model), which is more suitable for the actual working conditions of the human ear, this study has combined with the energy algorithm to establish the noise annoyance factor (BP), which can accurately identify the main frequencies in the noise signal that affect the sound quality. Meanwhile, they also have a vital role in analyzing the frequency structure of the movement. This research verifies the accuracy of noise annoyance evaluation (D) by analyzing the simulation signal, vacuum cleaner working signal, and fan heat dissipation signal. The noise annoyance factor (BP) is used to locate the center frequency range of a group of acoustic signals that produce the most significant noise annoyance to achieve the purpose of targeted noise reduction. This study provided a new solution for sound quality evaluation and targeted noise reduction.

Inverse model-based detection of programming logic faults in multiple zone VAV AHU systems

Implementation of sequences of operation for heating, ventilation, and air conditioning (HVAC) systems into a building automation system (BAS) is a critical process for building performance. Mistakes are commonly made while interpreting the sequences of operation from the mechanical design, converting them into BAS programs, and making ad-hoc changes to the BAS programs to address occupant complaints. This paper presents a novel inverse model-based fault detection and diagnostics (FDD) method for the discovery of BAS programming logic faults in variable air volume (VAV) air handling unit (AHU) systems. Using widely available BAS trend data types, the method first trains inverse models characterizing the heat and air mass balance of a VAV AHU system’s mixing box, heating and cooling coils, VAV terminal units, and zones. Then, the expected operational behaviour of the VAV AHU system is constructed by using ASHRAE Guideline 36 sequences of operation and the trained inverse models. Deviations from the expected operation are treated as the symptoms for the detection of programming logic faults. The method is demonstrated with BAS trend data from a 41-zone VAV AHU system in Ottawa, Canada. Two faults in supply air temperature and pressure reset programs are detected, significantly increasing fan electricity and heating energy use.

Research on Thermal Design of Server Structure Based on LRM Mode

Aiming at the module heat dissipation problem of a military domestic LRM mode server, a thermal design which can improve the module cooling efficiency and equipment integration is proposed. The design can realize the easy heat dissipation and high integration of on-board equipment. Through the design of fan device, module cooling and heat pipe, the heat dissipation efficiency of the server was improved, and the heat dissipation capacity of the module was improved. Thus the integration degree of on-board equipment was improved. The designed server was thermally analyzed and tested at + 65 °C. By comparing the experimental results with the thermal analysis results, the conclusion proved the correctness and feasibility of the research content in this paper.

Energy performance criteria for residential buildings: A comparison of Finnish, Norwegian, Swedish, and Russian building codes

Building code are considered to be an effective policy tool to reduce energy use in buildings. In practice, national priorities influence the indicators and criteria adopted in the building codes. Consequently, neighbouring countries with similar climate conditions may use different criteria in their building codes to regulate the energy performance. In this paper, the energy performance criteria and their relative stringency in the latest residential building codes of Finland, Norway, Sweden and Russia are compared. The study is based on energy performance evaluations of one single-family building and one multi-family building, located in the north of Sweden. Both buildings complied with the Norwegian and Russian building code. However, the buildings did not comply with the specific fan power and heat loss criteria in the Finnish building code. Additionally, the single-family building did not comply with the specific primary energy and electric powerdemand criteria in the Swedish building code when heated by an electric heater. The national standard input data were found to have a large influence on the buildings’ compliance with the studied energy use criteria. Policy implications of the results are discussed.

The De-Icing Comparison Experiment (D-ICE): a study of broadband radiometric measurements under icing conditions in the Arctic

Abstract. Surface-based measurements of broadband shortwave (solar) and longwave (infrared) radiative fluxes using thermopile radiometers are made regularly around the globe for scientific and operational environmental monitoring. The occurrence of ice on sensor windows in cold environments – whether snow, rime, or frost – is a common problem that is difficult to prevent as well as difficult to correct in post-processing. The Baseline Surface Radiation Network (BSRN) community recognizes radiometer icing as a major outstanding measurement uncertainty. Towards constraining this uncertainty, the De-Icing Comparison Experiment (D-ICE) was carried out at the NOAA Atmospheric Baseline Observatory in Utqiaġvik (formerly Barrow), Alaska, from August 2017 to July 2018. The purpose of D-ICE was to evaluate existing ventilation and heating technologies developed to mitigate radiometer icing. D-ICE consisted of 20 pyranometers and 5 pyrgeometers operating in various ventilator housings alongside operational systems that are part of NOAA's Barrow BSRN station and the US Department of Energy Atmospheric Radiation Measurement (ARM) program North Slope of Alaska and Oliktok Point observatories. To detect icing, radiometers were monitored continuously using cameras, with a total of more than 1 million images of radiometer domes archived. Ventilator and ventilator–heater performance overall was skillful with the average of the systems mitigating ice formation 77 % (many >90 %) of the time during which icing conditions were present. Ventilators without heating elements were also effective and capable of providing heat through roughly equal contributions of waste energy from the ventilator fan and adiabatic heating downstream of the fan. This provided ∼0.6 ∘C of warming, enough to subsaturate the air up to a relative humidity (with respect to ice) of ∼105 %. Because the mitigation technologies performed well, a near complete record of verified ice-free radiometric fluxes was assembled for the duration of the campaign. This well-characterized data set is suitable for model evaluation, in particular for the Year of Polar Prediction (YOPP) first Special Observing Period (SOP1). We used the data set to calculate short- and long-term biases in iced sensors, finding that biases can be up to +60 W m−2 (longwave) and −211 to +188 W m−2 (shortwave). However, because of the frequency of icing, mitigation of ice by ventilators, cloud conditions, and the timing of icing relative to available sunlight, the biases in the monthly means were generally less than the aggregate uncertainty attributed to other conventional sources in both the shortwave and longwave.

Variable air supply velocity of forced-air precooling of iceberg lettuces: Optimal cooling strategies

The air supply velocity has a direct impact on the cooling rate and energy consumption for forced air precooling of horticultural produce, which was often investigated at a constant air supply velocity throughout the whole precooling process previously. In this paper, the effects of different constant air supply velocity on cooling time, uniformity, heat load and energy consumption during different precooling stages were analyzed theoretically by numerical simulation. The simulated results are consistent with the experimental data. The analyzed results showed that the air supply velocity had less influence on the half cooling time, but it had significant impact on energy consumption whether before or after half cooling time, especially when air supply velocity exceeds 2 m/s. With the increased air supply velocity, the internal temperature gradient of individual product and cooling uniformity after half cooling time were all enhanced. Furthermore, from half cooling time to 7/8 cooling time, the proportion of fan heat load increased gradually with the precooling going on and became the main heat load (more than 50%), which means the refrigerating capacity is mainly used to remove the heat generated by ventilating fan in the later stage of precooling. Finally, a novel precooling strategy (variable supply air velocity precooling) was proposed and a method to determine optimal precooling condition from four constant and five variable supply-air velocity plans was established.

Experimental investigation of heat transfer performance of a heat pipe combined with thermal energy storage materials of CuO-paraffin nanocomposites

As the phase change material (PCM), pure paraffin wax is mixed with CuO (high heat conduction) and Span-80 (as a dispersant) in this research. The CuO/paraffin nanocomposite PCMs is synthesized with mass fractions of 0.3%, 0.6%, 0.9% and 1.2% by a two-step method. Dispersion stability and nanoparticle morphology of CuO/paraffin nanocomposite PCMs are analyzed by using a spectrophotometer and a scanning electron microscopy. Thermal conductivity and phase change latent heat of CuO/paraffin nanocomposite PCMs are investigated by changing the nanoparticle mass fraction. In addition, this paper investigates heat transfer characteristics of the heat pipe-PCMs module and effects of fan power and heating power on the performance of the cooling module. Results show that the thermal conductivity of the PCMs increases by 24.4% when 1.2% CuO nanoparticles are added into the paraffin, whereas the latent heat of phase change decreases by 1.5%. Compared to without PCMs, the heat pipe with 1.2% CuO/paraffin composite at 10 V fan voltage shows 17.2% reduction of the evaporator temperature. In addition, it is found that both a high fan voltage and a high mass fraction of CuO nanoparticles can significantly improve the heat transfer characteristics of the evaporation.

Heat-Dissipation Performance of Nanocomposite Phase-Change Materials in a Twin-Heat-Source System

In this paper, pure paraffin was mixed with CuO (high thermal conductivity) and Span-80 (as a dispersant). The CuO/paraffin nanocomposite phase-change materials (PCMs) were synthesized with mass fractions of 0.3%, 0.6%, and 1.2%, by a two-step method. Heat-transfer characteristics of the heat-pipe–PCMs module and effects of fan power and heating power on the performance of the cooling module in a twin-heat-source system were studied. For two heat sources under 10 W–10 W (heat source 1 with a power of 10 W and heat source 2 with a power of 10 W), the paraffin wax decreases the evaporator temperature by 14.4%, compared with cases without PCMs.

Analysis and comparison of potential power and thermal management systems for high-speed aircraft with an optimization method

• An advanced PTMS with an indirect regenerative air cycle is analyzed. • A comparison based on minimum fuel weight penalty optimization is proposed. • Optimal matching of the PTMS and flight mission is achieved at Mach 1-4.4. • The PTMS with a ram air bleed mode is suitable for Mach 3.4–4.4 cruise aircraft. Under the dual effects of aerodynamic heating and high-power electronic equipment heating, the heat sink and power demand of advanced high-speed aircraft have been exponentially rising, which seriously restricts the aircraft performance. To improve system cooling and power supply performance and reduce engine performance loss, a power and thermal management system (PTMS) with high performance, low energy consumption, and light weight urgently needs to be developed. In this paper, three modes of a potential PTMS with different heat sinks and bleed air sources are further discussed to analyze and compare the optimal matching with the flight mission at Mach 1–4.4. The equivalent mass method is used to uniformly assess the costs of the fixed weight, bleed, resistance, etc. as a function of the fuel weight penalty, which is chosen as the optimization objective. The optimization variables consist of the compressor outlet temperature, cooling air flow rate, and fan duct heat exchanger structure size. The results show that the intermediate-stage bleed air and fan duct heat sink are more suitable when the Mach number is less than 2, but the ram air bleed is highly suitable for flight missions at a high Mach number. Especially at Mach 3.4–4.4, the ram air bleed mode can respond to the cooling and power demands with a simple architecture.

Development of Cooling Fan Model and Heat Exchange Model of Condenser to Predict the Cooling and the Heat Resistance Performance of Vehicle

<div class="section abstract"><div class="htmlview paragraph">The cooling performance and the heat resistance performance of commercial vehicle are balanced with aerodynamic performance, output power of powertrain, styling, cost and many other parameters. Therefore, it is desired to predict the cooling performance and the heat resistance performance with high accuracy at the early stage of development. Among the three basic forms of heat transfer (conduction, convection and radiation), solving thermal conduction accurately is difficult, because modeling of “correct shape” and setting of coefficient of thermal conductivity for each material need many of time and efforts at the early stage of development. Correct shape means that each part should be attached correctly to generate the solid mesh with high quality. Therefore, it is more efficient and realistic method to predict the air temperature distribution around the rubber/resin part instead of using the surface temperature at the preliminary design stage. The air temperature distribution in the engine compartment is dominated by the flow distribution from fans, the heat rejected by heat exchangers, AC-generator and the convecting heat by surface temperature of parts. In the case of steady middle/high vehicle speed modes, thermal convection has larger effects on the air temperature distribution. To predict these phenomena with high accuracy, the fan model and condenser model are developed. The fan model provides the accurate P-Q performance based on a specification and the flow distribution based on the LES results of the sliding mesh method with low computational cost. The heat rejection by the condenser is concentrated around the inlet tube of core. To reproduce this distribution, the phase change of refrigerant is solved in the condenser model. The accuracy of these models is confirmed by using component experiments and vehicle measurements. Accuracy of heat-exchanger coolant temperature is within 2K and air temperature in the engine compartment is 5K respectively.</div></div>

Investigation on ash fouling formation of induced fan blade and heat exchanger surface in a 1000MW coal-fired power plant

The control of fouling deposition on the main equipment has always been an im-portant issue concerned by scientific research and industrial application. How-ever, severe fouling deposits on the induced fan blade and the low temperature economiser were found in a 1000 MW coal-fired power plant with ultra-low emission. The deposit samples were collected and analysed through X-ray dif-fraction spectrometer, X-ray fluorescence, elemental analyser and SEM with en-ergy dispersive spectrometers. The result shows that the deposits are mainly composed of tschermigite (NH4)Al(SO4)2 ? 12H2O, letovicite (NH4)3H(SO4)2, cal-cium sulphate CaSO4, and quartz SiO2. The ammonium sulphate is the main component of the fouling deposits. It acts as an adhesive and makes an important contribution to the deposition. The analysis shows that the ammonia slip from denitrification system and the unreasonable temperature setting are the main reasons for fouling deposition. It is suggested that the high concentration of am-monium slip at denitrification system and the rapid condensation of the sulphuric acid mist at heat exchanger should be paid more attention in coal-fired power plants.

Fan Noise Control and Heat Dissipation Optimization of Commercial Vehicle Cooling System

Aiming at the problem of matching fan noise and heat dissipation in a commercial vehicle cooling system, it is proposed to reduce noise by changing the fan structure and to increase the windshield to block the hot air reflux. By changing the number of blades, wheel hub ratio, blade bending angle fan performance parameters, and the cooling fan mass flow rate and aerodynamic noise were simulated by CFD, the fan performance parameters were optimized. Then, the flow field and temperature field of engine cabin are analyzed. According to the analysis, the hot air reflux exists in the radiator, and the baffle is added to the upper part of the radiator and to the left and right sides of the radiator to block the reflux. The results show that the fan noise is reduced by 2.7 dB and the maximum temperature in the engine cabin is reduced from 417k to 392k.

Unjuk Kerja Kotak Pendingin Peltier dengan Unit Pembuang Panas Heat Sink Fin-Fan dan Double Fan Heat Pipe

Nowadays, technology is growing rapidly. A refrigerator is one of the technology applications by using heat transfer phenomena. However, the existing refrigerators in big size, need large power, and able to damage the ozone because most of the refrigerators utilize CFC. It is necessary to create a compact refrigerator with low energy needed and environmental friendly. In this study, a small cooler box of 24.5 cm x 20 cm x 28.5 cm with 2 modules Peltier SP 1848-27145 type arranged in cascade was used as a refrigerator. The data were logged by using the data logger DAQ MX 9714 NI that was connected to the PC by using LabView. In this experiment, 22 Watt of the electric power was used and 350 ml water was placed on the cooler box room. The results show that the temperature of the cooler box room with a single fan heat pipe is lower than the heat sink fin-fan. Furthermore, the temperature of the cooler box room with the single fan heat pipe where 350ml water was placed is lower than the cooler box room without the single fan. Moreover, the COP of the cooler box is significantly affected by the heat dissipation unit.

Caloric method for the energetic evaluation of decentralised domestic ventilation devices

In the context of this article, a caloric method for measuring the performance of alternating home ventilation devices (push-pull units) is presented. The simple and robust method provides both reliable and reproducible characteristic values. Based on this method, a test bench was developed and built. With this test bench the characteristic values (volume flow, heat recovery rate, temperature change rate) of series products can be measured. The aim of the investigation is the determination and evaluation of the possible parameters influencing the measurement. For this purpose, the parameters are illustrated on the basis of measured values from a defined test standard, consisting of a fan and electrical heating in a housing (so-called golden sample), as well as a pair of push-pull devices. As a result, suggestions for improvements to the previous procedure as well as approaches for further development are shown.