Several studies on vaccines and medicines against virus-based illnesses (COVID-19, SARS, MERS) are being conducted worldwide. However, virus mutation is an issue. Therefore, inactivation and disinfection of viruses are crucial. This paper presents a method for virus inactivation by physical techniques. The infrared (IR) technique is preferred over other disinfection techniques such as ultraviolet (UV) and chemical disinfectants (alcohol) due to the associated health and environmental benefits. In this study, IR sources with various wavelengths were characterized and a far infrared (FIR) source was used to inactivate viruses. FIR sources have a therapeutic effect on the human body and have been used in medical centers. Virus spread is highly affected by environmental conditions such as temperature, humidity, and airflow. A setup with IR sources, an IR camera, an automatically controlled humidity chamber, and an airflow unit was constructed to study the viability of viruses in stationary droplets as a function of relative humidity and temperature. Bacteriophage was used as a model organism for studying enveloped viruses such as influenza and coronavirus. IR techniques were used for studying virus inactivation. The effect of various physical conditions such as temperature, humidity, and airflows was considered to study the effect of radiation on the stationary droplets of . All measurements were performed under laboratory conditions with controlled temperature and humidity. The IR camera system was used to measure the surface temperature of Phi6 suspension droplets. The samples subjected to IR radiation were processed for plaque assay preparation and counting. Measurements were carried out to reduce and eliminate droplets, which are one of the transmission pathways of viruses. IR was radiated in closed and open-air conditions with appropriate humidity and temperature. This study reports the effective inactivation of viruses by FIR. The inactivation rate under 50 %rh for IR radiated at 1.4 m height for 3 h in closed environmental chamber was 90%, and that under an airflow rate of 0.20 m/s for 10 min in open-air conditions at a height of 1.0 m was 45.7%.

A cooperative control strategy is proposed for the air conditioning (AC) system and ventilation system to reduce the risk of COVID-19 infection and save the energy of the AC system. This strategy integrates the dynamic model of the AC-cabin system, infection risk assessment, model predictive control (MPC) of the thermal environment inside the cabin, and ventilation control that considers passengers' sneezing. Unlike other existing AC system models, the thermal-health model established can describe not only the system performance but also the virus concentration and risk of COVID-19 infection using the Wells-Riley assessment model. Experiments are conducted to verify the prediction accuracy of the AC-cabin model. The results prove that the proposed model can accurately predict the evolution of cabin temperature under different cases. The cooperative control strategy of the AC system integrates the MPC-based refrigeration algorithm for the cabin temperature and intermittent ventilation strategy to reduce the risk of COVID-19 infection. This strategy well balances the control accuracy, energy consumption of the AC system, and the risk of COVID-19 infection, and greatly reduces the infection risk at the expense of a little rise in the energy consumption.

Recently, magnetic nanoparticles (MNPs) based hyperthermia therapy has gained much attention due to its therapeutic potential in biomedical applications. This necessitates the development of numerical models that can reliably predict the temporal and spatial changes of temperature during the therapy. The objective of this study is to develop a comprehensive numerical model for quantitatively estimating temperature distribution in the ferrofluid system. The reliability of the numerical model was validated by comparative analysis of temperature distribution between experimental measurements and numerical analysis based on finite element method. Our analysis showed that appropriate incorporation of the heat effects of electromagnetic energy dissipation as well as thermal radiation from the ferrofluid system to the surrounding in the modeling resulted in the estimation of temperature distribution that is in close agreement with the experimental results. In summary, our developed numerical model is useful to evaluate the thermal behavior of the ferrofluid system during the process of magnetic fluid hyperthermia.

This paper reports a heat transfer advancement in the cryogenic quenching process. An experiment was performed to evaluate the enhancement of quenching heat transfer by the use of metal tubes with low thermal conductivity coating layers. Four coating thicknesses with various coolant mass flow rates of liquid nitrogen were investigated. The results indicated that the tube inner surface coating greatly enhanced the quenching efficiency. The quenching efficiency was found to increase with increasing number of coating layers, and the efficiency also increased with decreasing mass flow rates. In general, the efficiencies cover a range between 40.6% and 80%. Comparing to the bare surface case, the percentage increase in the quenching efficiency was the minimum at 4.2% for a single coated layer at the highest flow rate and the maximum of 109.1% for four coated layers at the lowest flow rate. The coated tubes could save up to 53% in the amount of cryogen consumption.

NASA is designing an unmanned submarine to explore the depths of the hydrocarbon-rich seas on Saturn's moon Titan. Data from Cassini indicates that the Titan north polar environment sustains stable seas of variable concentrations of ethane, methane, and nitrogen, with a surface temperature near 93 K. The submarine must operate autonomously, study atmosphere/sea exchange, interact with the seabed, hover at the surface or any depth within the sea, and be capable of tolerating variable hydrocarbon compositions. Currently, the main thermal design concern is the effect of effervescence on submarine operation, which affects the ballast system, science instruments, and propellers. Twelve effervescence measurements on various liquid methane-ethane compositions with dissolved gaseous nitrogen are thus presented from 1.5 bar to 4.5 bar at temperatures from 92 K to 96 K to simulate the conditions of the seas. After conducting effervescence measurements, two freezing point depression measurements were conducted. The freezing liquid line was depressed more than 15 K below the triple point temperatures of pure ethane (90.4 K) and pure methane (90.7 K). Experimental effervescence measurements will be used to compare directly with effervescence modeling to determine if changes are required in the design of the thermal management system as well as the propellers.

We introduce here the finite volume formulation of the frequency-domain simplified spherical harmonics model with -th order absorption coefficients (FD-SP) that approximates the frequency-domain equation of radiative transfer (FD-ERT). We then present the FD-SP based reconstruction algorithm that recovers absorption and scattering coefficients in biological tissue. The FD-SP model with 3 order absorption coefficient (i.e., FD-SP) is used as a forward model to solve the inverse problem. The FD-SP is discretized with a node-centered finite volume scheme and solved with a restarted generalized minimum residual (GMRES) algorithm. The absorption and scattering coefficients are retrieved using a limited-memory Broyden-Fletcher-Goldfarb-Shanno (L-BFGS) algorithm. Finally, the forward and inverse algorithms are evaluated using numerical phantoms with optical properties and size that mimic small-volume tissue such as finger joints and small animals. The forward results show that the FD-SP model approximates the FD-ERT (S) solution within relatively high accuracy; the average error in the phase (<3.7%) and the amplitude (<7.1%) of the partial current at the boundary are reported. From the inverse results we find that the absorption and scattering coefficient maps are more accurately reconstructed with the SP model than those with the SP model. Therefore, this work shows that the FD-SP is an efficient model for optical tomographic imaging of small-volume media with non-diffuse properties both in terms of computational time and accuracy as it requires significantly lower CPU time than the FD-ERT (S) and also it is more accurate than the FD-SP.

This paper presents specific heat measurements for a synthetic polyolester (POE) based aluminum oxide (AlO) nanolubricant with a polymeric surfactant over a temperature range from approximately 4 °C to 45 °C. AlO nanolubricants with two nominal surface-area-based diameter nanoparticles were investigated: 20 nm and 40 nm. The number-based diameter of the nanoparticles, as determined by dynamic light scattering (DLS), were 112 nm and 148 nm, respectively. The nanoparticle mass fractions were varied from 0.076 to 0.249 for the 112-nm diameter nanolubricant, and from 0.059 to 0.394 for the 148-nm diameter nanolubricant. The measurements showed that the specific heat of the nanolubricant linearly increased with increasing temperature, and linearly decreased with respect to increasing nanoparticle mass fraction. The size of the nanoparticle was shown to have no effect on the magnitude of the specific heat of the nanolubricant. The measurements were compared with two existing models. The mass fraction weighted model exhibited excellent agreement with the measurements (within ±1.01%). In contrast, the volume mass fraction model failed to predict the measurements for most conditions to within ±5%.

An analysis of a circular thin-foil gage is presented that includes transient effects, convective heat transfer, and an arbitrary time-varying boundary condition at the foil edge to account for fluctuations in cooling water temperature. The governing energy equation is solved using Laplace transform to obtain the temporal and spatial temperature distributions of the foil. Under constant temperature at the foil edge and constant thermal radiative heat flux, closed-form response curves for the gage under various modes of heat transfer are provided. Steady-state results are also presented as limiting cases.