Internal Temperature Research Articles

BATTERY COOLING SYSTEMS OF ELECTRIC VECHILES

To enhance electric vehicle battery performance, the Battery Thermal Management System (BTMs) plays a crucial role by regulating internal battery temperature within optimal limits. Among the key components, the cooling system is paramount in maintaining this temperature range. Various cooling techniques such as Air Cooling (AC), Liquid Cooling (LC), Refrigerant Direct Cooling (RDC), Phase Change Material (PCM) based systems, Thermoelectric Cooling (TC), Heat Pipe Cooling (HPC), and Hybrid Cooling (HC) have been employed in electric vehicles. This paper provides an exhaustive review of these cooling systems, delineating their respective merits and demerits. The findings offer valuable insights for researchers delving into electric vehicle battery cooling technology. Keywords: Electric vehicle, battery, cooling system, thermal management system.

134 Does inclusion of high oleic soybeans in a swine finishing ration influence lipid oxidation and consumer taste panel preference?

Abstract The objective of this study was to determine if a swine finishing ration that included soybeans with greater concentration of oleic acid will have an impact on lipid oxidation and palatability of pork. Crossbred pigs [n = 72; initial body weight (BW) = 78 ± 9 kg] were blocked by BW, sex, and distributed within 18 pens. Each pen was randomly assigned to 1 of 3 experimental diets: a control soybean-meal (CTRL), extruded conventional soybean (CONV), and extruded high oleic acid soybean (TRU). Six different harvest groups (n = 12/group) were created across treatments to ensure uniformity of final BW. Therefore, experimental diets were offered to animals for 34, 37, 41, 42, 48, or 50 d, until all pigs reached 118 ± 5 kg. Carcasses were harvested, and chilled (2°C) for 24 h, before fabricating one 2.5 cm chop from the 11th rib of the right carcass side. The chops were vacuum packaged, aged for 7 d at 2 oC, and frozen (-18 oC) for later sensory analysis. Pork chops were thawed and cooked to 71 oC peak internal temperature (AMSA sensory guidelines) and fed to 115 consumers that rated overall liking, flavor, tenderness, juiciness, and presence of off flavors using hedonic scales. Also, a 50 g sample was obtained from each loin at the 12th rib, aged for 7 d and frozen at -80 oC for evaluation of malondialdehyde (MDA) as indicator of lipid oxidation. Subcutaneous fat samples were obtained from the first thoracic vertebra, frozen, and saved for fatty acid analysis. Data were analyzed using the MIXED procedure of SAS where diet was the main effect, while pen and breed were random effects. Repeated measures were used to analyze the consumer panel. Differences were considered significant at P ≤ 0.05 with pen as experimental unit. There were no significant differences (P > 0.05) for consumer perception of overall like, pork flavor, and presence of off flavors. Experimental diets impacted the perception of juiciness and tenderness (P < 0.05), where CONV was perceived as juicier and more tender than CTRL and TRU. As expected, diet affected the fatty acid profile of subcutaneous fat (P < 0.0001), with TRU having the greatest percentage for oleic (43.9 %), CONV the greatest percentage for linoleic and linolenic (17.8 and 1.3 % respectively), and CTRL for saturated fatty acids (34.5 %). Surprisingly, the lipid oxidation was not affected by the diet (P > 0.05). These results indicate that feeding extruded high oleic soybeans during the finishing period can modify the fatty acid profile in pork by improving the percentage of unsaturated fatty acids, so these soybeans can be considered as an alternative to improve nutritional value of pork without increasing the lipid oxidation or affecting the consumers acceptability.

Thermal and hydraulic performance of volumetrically heated triply periodic minimal surface heaters

Advanced heat transfer surfaces, mainly Triply Periodic Minimal Surfaces (TPMSs) have great potential to increase heat transfer performance over traditional heat transfer surfaces due to their tortuous flow path and higher surface area-volume ratio. The emergence of additive manufacturing of nuclear fuel motivates experimental investigation of such advanced geometries in the context of a nuclear reactor core. This study employed a novel method to explore the performance of gyroid and diamond TPMS geometries. Volumetrically heated heaters were additively manufactured from conductive polymer filament, and airflow was used to simulate the convective heat transfer from the core within a nuclear reactor. The mass flow and volumetric generation rates were varied, local Nusselt number correlations were obtained using embedded thermocouples to measure the solid and fluid temperature, and friction factor correlations were developed using differential pressure measurements. The gyroid TPMS presented a friction factor 1.5 times higher than the diamond TPMS and 90 times that of the rod bundle. TPMS geometries showed Nusselt numbers 8–10 times higher than that of the rod bundle, also maintaining colder internal temperatures, which suggested that they could sustain 250–275 % higher power density than the rod bundle for a given centerline temperature. Hence, having the potential to greatly increase the safety margins and power output of a nuclear reactor core with similar volume.

Biomimetic phase change capsules with conch shell structures for improving thermal energy storage efficiency

Latent heat storage system utilizing a packed-bed setup with encapsulated phase change materials (EPCMs) can address the issues of mismatched energy supply and demand, in addition to preventing the leakage concerns associated with unencapsulated PCMs, which has a broad application prospect. Drawing on the principles of biomimicry, this work proposes bionic-conch and bionic-mitochondrial encapsulation models for PCMs and analyzes the heat transfer performance with different structures. Significantly, the thermal energy storage efficiency of the bionic-conch structure surpassed that of the bionic-mitochondrial and straight-fin structures by 43.11 % and 14.62 %, respectively. The enhanced thermal energy storage efficiency of the bionic-conch is attributed to the spiral fins within, which considerably amplify the heat exchange surface area. Furthermore, in order to obtain the bionic-conch capsule structure with optimal thermal properties, the present work investigates the influence of fins on the melting characteristics of PCMs. The results show that increasing fins empower the thermal energy storage efficiency by 402.89 % and thermal response rate by 616.93 %, respectively. However, there is an issue of slow melting process in the annular region and incorporating an array of a slightly off-center heat-conducting ring (SOHR) is considered to enhance localized heat transfer. The suggest that it can alleviate the problem of slow heat transfer rate in the local annular region and increase the average internal temperature. Furthermore, in order to compensate for the loss of thermal energy capacity of the fin structure, this work also investigated the effect of different wall thicknesses on the thermal performance of the phase change capsule. Interestingly, decreasing the wall thickness significantly increases the heat capacity. In concrete terms, the thermal energy capacity of 0.5 mm wall thickness is increased by 22.87 % compared to 2 mm. This study may provide new enlightenment for the optimization of green energy.

Intelligent Control Based on Usage Habits in a Domestic Refrigerator with Variable Speed Compressor for Energy-Saving

Maintaining adequate temperatures for preserving food in a domestic refrigerator is a task that is affected by several factors, including the daily use of the appliance. In this sense, this work presents the development of a novel control system based on fuzzy logic that considers usage habits such as the amount of food entering the refrigerator and the frequency of opening doors. Thus, the control comprises input variables corresponding to the internal temperatures of both compartments, the thermal load entered, and the refrigerator door-opening signal. By simulating the usage habits of a refrigerator with a variable-speed compressor, the control performance was evaluated. The results showed that implementing fuzzy control using usage habits was robust enough to maintain adequate thermal conditions within the compartments and a lower thermal fluctuation concerning the reference control of the refrigerator (factory control). In terms of energy, the fuzzy control resulted in an energy saving of 3.20% with the refrigerator empty (without thermal load) compared to the reference control. On the other hand, the individual integration of the thermal load in the fuzzy control resulted in 2.08% energy savings and 5.45% for the integration of the thermal load compared to the reference control. Finally, considering the combination of usage habits, the fuzzy control presented a higher energy consumption than the reference control, around 9.7%. In this case, the fuzzy control maintained more favorable thermal conditions in both compartments, whereas the reference control presented a warmer thermal condition in the freezer.

Mitigating urban heat island and enhancing indoor thermal comfort using terrace garden

The United Nations advocates for sustainable urban planning and design, emphasizing green infrastructure initiatives to mitigate urban heat island effects and enhance the resilience and livability of cities globally. To address urban heat challenges, a study was conducted in Chennai, India, from April to June 2023. The study focused on assessing temperature dynamics on a building's terrace by comparing a well-maintained garden area with an exposed region. Temperature and humidity sensors were deployed in both the garden and exposed areas of the terrace, as well as within rooms beneath it, to monitor hourly temperature fluctuations. The findings indicate a significant reduction in internal room temperatures in areas with rooftop gardens, ranging from 4 to 11 °C, depending on the time of year and sun's position, compared to rooms with fully exposed roof configurations. Additionally, simulation studies were performed to validate these findings, suggesting that optimizing the distribution of soil beds and plant density across the roof could yield an additional temperature reduction of 3–4 °C, resulting in an overall difference of up to 14–15 °C. The study highlights the efficacy of rooftop gardens in providing cooling effects during daylight hours and maintaining temperature parity post-sunset. Through analysis of sensor data, the research elucidates the intricate relationship between green infrastructure and thermal comfort, offering insights for energy-efficient building design and resilient urban planning. The findings underscore the potential of rooftop gardens in fostering a more comfortable, energy-efficient, and sustainable urban living environment.

Molecular dynamics simulations into rolling scraping of nickel-copper bilayer film

In order to investigate the nanoscale friction mechanism and deformation behavior of nickel-copper bilayer film under rolling scraping, the effects of different factors during friction process such as the translation velocity, rotation velocity, radius of abrasive grain, contact depth, texture direction and crystallographic orientation are analyzed through molecular dynamics methods in terms of contact force, atomic lattice structure, internal substrate dislocation, kinetic energy and temperature. Results show that the contact force increases with the increase of the translation velocity or the decrease of the rotation velocity. Abrasive grains in a purely rolling state cause the most serious damage to the substrate. The contact force increases with the increase of contact depth or the decrease of abrasive grain radius. The crystallographic orientation has a significant effect on rolling scraping process and there is a crystallographic orientation with the minimum contact force. The degrees of substrate dislocation and the numbers of lattice reconstruction atoms under different factors and levels vary widely.

A novel thermal-tailored strategy to mitigate thermal cracking of cement-based materials by carbon fibers and liquid-metal-based microencapsulated phase change materials

Massive concrete structures are susceptible to thermal cracking due to the large surface-to-internal temperature gradients induced by the exothermic cement hydration, threatening their durability and safety. This study explored a novel thermal-tailored strategy to mitigate thermal cracking of cement-based materials by incorporating carbon fibers (CF) and liquid-metal-based microencapsulated phase change materials (MEPCM). Specifically, spherical MEPCM composed of In-Bi-Sn alloy cores coated by polyvinyl alcohol shells was prepared through a high-speed liquid-phase dispersion method, with average diameters of 36.26 μm and a high volumetric latent heat of 214 MJ/m3. The synergistic effect of CF and MEPCM on the microstructure, mechanical and thermal properties of cement mortars was further investigated. Upon adding 0.3 wt% of CF and 3.2 vol.% of MEPCM, the flexural strength of cement mortars exhibited a significant increase of 30.3 %. Microanalysis revealed that the molten MEPCM could flow to fill the pores and microcracks within its surrounding matrix and form a network skeleton with well-dispersed CF, imparting flexibility to the typically rigid cement hydrates. By this way, the thermal conductivity of cement mortars was increased by 21.7 % and internal temperature rise was decreased by 12 ℃ by adding 4.8 vol.% of MEPCM, contributing to the mitigation of risks associated with thermal cracking. The research outcomes will provide valuable insights into the development of thermal cracking-resistant cement-based materials in a highly efficient way.

Experimental investigation on the stability and heat transfer enhancement of phase change materials composited with nanoparticles and metal foams

Conventional phase change materials (PCMs) possess the challenge of low thermal conductivity, which hinders the energy exchange rate and storage efficiency. PCMs composited nanoparticles and metal foams have been a proven solution to enhance the thermal characteristics of PCMs. In this work, three enhanced PCM composites including nanoparticle/paraffin, metal-foam/paraffin and nanoparticle/metal-foam/paraffin were prepared using fusion blending and vacuum impregnation method. The effects of different nanoparticles with different mass fractions on the stability and heat storage and release characteristics of nanoparticle/paraffin were investigated. Compared with paraffin, the melting time and solidification time of nano-metal/paraffin are reduced by a maximum of 30.18 % and 43.15 %, respectively. In addition, the effect of pore density of metal foam on natural convective heat transfer process was evaluated. The results showed that the stability in descending order is as follows: nano‑aluminum, nano‑copper and nano‑silver. The optimal mass fraction of nanoparticles with good stability was 1.5 wt% (copper), 1.0 wt% (silver), 1.5 wt% (aluminum), respectively. The metal foam makes the internal temperature distribution of PCMs more uniform in the heat transfer process, while inhibiting the convective heat transfer process. With the increase of pore density, the effect on natural convection heat transfer process rises. When the PPI (pores per linear inch) of foamed metal is greater than 40, the natural convection process can be inhibited, obviously. The foam metal has a more significant effect on the heat transfer performance of nanoparticle/metal-foam/paraffin than that of the nanoparticles. The economic benefits of nanoparticle/paraffin, metal-foam/paraffin and nanoparticle and metal foam composite phase change materials are progressively decrease, with MFP being suitable for applications with high economic budgets.

The Effect of the Temperature Increase on Heat Demand Calculation for Building in the Polish Climatology

Heat demand calculation procedures for buildings are currently being conducted based on the Polish Standard grounded on the European Standard for heat losses methodology. Poland was divided into several climatic zones with given calculations and annual average external air temperature values. In each zone, the technical committee gives the temperature that must be considered. The data included in the Polish Standard preparation concern several years backwards. However, throughout the previous years, we have observed the tendency of the temperature to increase throughout the year, not only in Poland. The phenomenon provides scientists with the conclusion that the temperatures will continue to increase yearly. The low temperatures in the winter season will no longer occur. Therefore, it is necessary to analyse the possibility of lowering the heat demand calculation, including the actual prevailing temperature values. The study was conducted regarding possible economic benefits for the building users due to the lower temperature difference between the internal and external temperatures. Three types of heating systems were analysed. The calculations were conducted for air to water heat pump, pellet boiler and gas condensing boiler, proving that regarding the actual meteorological data, the average annual cost reduction will be in the range of 858 PLN to 1,035 PLN.

Impact of Various 10-min Cooling Breaks on Internal Body Temperature Responses During Subsequent Intermittent Exercise in the Heat: Application to Tennis

Impact of Various 10-min Cooling Breaks on Internal Body Temperature Responses During Subsequent Intermittent Exercise in the Heat: Application to Tennis

Ultra-Fast Preparation of High-Strength Polymer Concrete via Frontal Polymerization at Room Temperature.

Concrete, in particular application scenarios, such as crack repair, disaster rescue and relief, and 3D printing, needs to be cured quickly. In this work, a novel synthesis strategy, UV-initiated frontal polymerization (FP), for fast preparation of high-strength polymer concrete at room temperature is proposed, and the whole fabrication progress within several minutes, in which coarse aggregates and a small amount of short carbon fibers (CF) are used to enhance mechanical properties and heat conduction and reduce the amounts of chemical adhesives. SEM, DSC, MIP, Ultra depth of field microscope, and Rheometer are employed to characterize the properties of chemical adhesives, polymer concrete, and polymerization process. In addition, the finite element method is used to investigate the internal temperature field status of the FP process. The results indicate that the compressive and flexural strengths of the polymer concrete with 1.0wt%-1mm-CF-50vol.%-quartz sand exceeded 70 and 20MPa, respectively, in which the average self-propagation velocity reached 58mmmin-1. The investigation provides a promising approach for the rapid construction of structural facilities, emergency repair after disasters, 3D printing concrete, etc.

An innovative PCM-modified lining system for energy tunnel: From concept to numerical investigations

The rich geothermal stored in rock mass would result in high temperature to tunnels. This not only makes condition worse to workers, but also wastes geothermal energy and increases cost to adjust the internal environmental temperature. This motivates the present feasibility study on an innovative PCM-modified lining system of conventional energy tunnel, which generally makes use of ground source heat pump (GSHP). That is, the PCM-modified concrete regulates the thermal properties of tunnel linings installed with pipe loops of GSHP. To verify the concept of the new system, a finite element model (FEM) describing it is established, based on a case of high geothermal tunnel. Simulation of the heat conducting process of tunnel linings starting from hydration of cement during cast-in-place concrete, thermal conductivity from surrounding rock mass, circulating of GSHP, phase change within the PCM-modified linings, and boundary effect since ventilation are considered in the modeling. The results demonstrate that the new system would mitigate the level of thermal discomforts during construction stage, and it can improve the stability and efficiency in energy extraction in operation stage. Parametric study on the GSHP with PCM-modified linings gives that the better heat reduction performance can be obtained with the smaller intermittent ratio (IR) of GSHP, smaller temperature range of phase change, and larger latent heat, and higher exchanger rate can be obtained with the larger IR and larger latent heat.

An improved methodology for thermal calculation and design optimization of a thermosiphon waste heat boiler for CCPP

The study is dedicated to enhancing design and computational methodologies for thermosiphon waste heat boilers (WHB) within combined cycle power plants (CCPP). The optimized WHB design and an improved thermal calculation approach are shown. The efficiency of the proposed WHB has been improved by optimizing the area and arrangement of the surface. The novel method incorporates considerations for the internal thermal resistance within thermosyphons and the graded velocity of natural circulation within the evaporation circuit. To refine the calculation method, empirical and experimental data concerning internal temperature gradient in thermosiphon functioning within a heat load spectrum of up to 17 kW/m2, were used. Important findings include three categories. Firstly, increasing the number of sections will slightly increase capital costs and decrease WHB gas temperature, which could be neglected by the unification of thermosiphon sections. Secondly, by applying this modified methodology to a power plant facility featuring a 6700 kW gas turbine engine (GTE), notable adjustments in thermal power were realized, amounting to 157 kW (approximately 6 %), along with corresponding electrical power adjustments of 149 kW (approximately 2 %). Third, the new method is limited to a GTE power of up to 10 MW due to the experimental data used for validation.

Temperature Self-Compensating Intelligent Wireless Measuring Contact Lens for Quantitative Intraocular Pressure Monitoring.

Flexible bioelectronic devices that can perform real-time and accurate intraocular pressure (IOP) monitoring in both clinical and home settings hold significant implications for the diagnosis and treatment of glaucoma, yet they face challenges due to the open physiological environment of the ocular. Herein, we develop an intelligent wireless measuring contact lens (WMCL) incorporating a dual inductor-capacitor-resistor (LCR) resonant system to achieve temperature self-compensation for quantitative IOP monitoring in different application environments. The WMCL utilizes a compact circuitry design, which enables the integration of low-frequency and high-frequency resonators within a single layer of a sensing circuit without causing visual impairment. Mechanically guided microscale 3D encapsulation strategy combined with flexible circuit printing techniques achieves the surface-adaptive fabrication of the WMCL. The specific design of frequency separation imparts distinct temperature response characteristics to the dual resonators, and the linear combination of the dual resonators can eliminate the impact of temperature variations on measurement accuracy. The WMCL demonstrates outstanding sensitivity and linearity in monitoring the IOP of porcine eyes in vitro while maintaining satisfactory measurement accuracy even with internal temperature variations exceeding 10 °C. Overcoming the impact of temperature variations on IOP monitoring from the system level, the WMCL showcases immense potential as the next generation of all-weather IOP monitoring devices.

Numerical simulation of frost heaving damage of earth-rock dam berms in cold regions with thermo-hydro-mechanical coupling

In order to investigate the freezing damage problem of berms of earth-rock dams in cold regions, an earth-rock dam in a cold region was selected as the research object in this study. A finite element model, considering the effect of thermo-hydro-mechanical coupling, has been developed to solve the problem by combining the characteristics of the earth-rock dam. The whole process of freezing damage of berms under the influence of the reservoir level and the water migration of the dam filling was investigated, and the laws in temperature, humidity and displacement of earth-rock dams were analyzed. The calculated displacement field was then compared with the measured frozen deformation data to validate the results of the finite element simulation. The results showed that the freezing influence range of the dam slope was about 2 m, the range of temperature influence on the dam slope mainly depended on the depth of freezing, and the temperature change in the shallow range (0–2 m) of the dam slope was influenced by the outside air temperature. Also, the internal temperature of the dam body was small relative to the shallow dam slope, and there was a certain hysteresis. In addition, the effect of negative temperature was such that the shallow pore water phase of the dam slope turned into ice, manifesting macroscopically as a reduction in unfrozen water content. Water phase change, water migration from the dam filling to the dam slope, and the movement of the ice peak towards the dam body were found to be the main causes of berm freezing and expansion damage. The calculated amount expansion (due to freezing) of the dam slope was found to be in the range of 20–30 cm with a maximum value of 36 cm, which was consistent with the measured results. It was also found that the freezing and expansion damage of the berm is mainly caused by the joint action of freezing and expansion of the soil and rock mixture such as gravel bedding and dam filling, as well as the ice thrust force. It is expected that the results of this research can provide a basis for the design of berms of earth-rock dams in cold regions.

Real-Time Temperature Monitoring of Lithium Batteries Based on Ultrasonic Technology.

Electrochemical energy storage stations serve as an important means of load regulation, and their proportion has been increasing year by year. The temperature monitoring of lithium batteries necessitates heightened criteria. Ultrasonic thermometry, based on its noncontact measurement characteristics, is an ideal method for monitoring the internal temperature of lithium batteries. In this study, temperature and ultrasonic time delay measurement experiments were conducted on 18650 lithium batteries and laminated and wound lithium batteries to obtain the corresponding relationship between temperature and time delay and validate the temperature measurement for the same type of battery. The experimental results show that (1) the ultrasonic temperature measurement technique exhibits a relatively large error when used for 18650 Li-ion batteries under experimental conditions; (2) in the experiments on laminated and wound soft-pack lithium batteries, the relationship between temperature and time delay exhibits a nonlinear characteristic; and (3) under the experimental conditions, the ultrasonic temperature measurement errors were ±1.1 °C for stacked Li-ion batteries and ±1.4 °C for wound Li-ion batteries.

Validation of a Simulated Commercial English Muffin Baking Process to control Salmonella Contamination

A validation study was conducted to investigate the effect of the English muffin baking process to control Salmonella contamination and to study the thermal inactivation kinetic parameters (D- and z-values) of Salmonella in English muffin dough. The unbleached bread flour was inoculated with 3 serovar Salmonella cocktail (Salmonella serovars viz., Newport, Typhimurium, and Senftenberg), and dried back to its preinoculated water activity levels with 7.46 ± 0.12 log CFU/g of Salmonella concentration. The Salmonella inoculated flour was used to prepare English muffin batter and baked at 204.4°C (400°F) for 18 min and allowed to cool at ambient air for 15 min. The English muffins reached 99 ± 0°C (211.96 ± 0.37°F) as their maximum mean internal temperature during baking. The pH and aw of English muffin dough were 5.01 ± 0.01 and 0.947 ± 0.003, respectively. At the end of the 18−min baking period, the Salmonella inoculated English muffins recorded a more than 5 log CFU/g reduction on the injury-recovery media. The D-values of 3 serovar cocktails of Salmonella at 55, 58.5, and 62°C were 42.0 ± 5.68, 15.6 ± 0.73, and 3.0 ± 0.32 min, respectively; and the z-value was 6.2 ± 0.59°C. The water activity (aw) of the English muffin crumb (0.947 ± 0.003 to 0.9557 ± 0.001) remained statistically unchanged during baking, whereas the aw of the muffin crust decreased significantly (0.947 ± 0.003 to 0.918 ± 0.002) by the end of 18 min of baking. This study validates and documents the first scientific evidence that baking English muffins at 204.4°C (400°F) for 18 min acts as an effective kill step by controlling Salmonella population by >5 log CFU/g.

Wet Aging USDA Select Beef Strip Steaks: Implications on Consumer Acceptability, Demand, and Product Selection

The objective of this study was to determine if wet aging increases the value and demand for lower-quality USDA-grade beef steaks. USDA Select boneless beef loins (NAMP #180) were dorsally divided into 4 equal portions, which were randomized to receive 0, 7, 14, or 21 d of wet aging. A total of twenty 2.5-cm-thick steaks from each aging time (n = 20 steaks per aging treatment) were cooked to an internal temperature of 71°C, cubed, and served to a consumer panel (N = 126), which evaluated acceptability using a 9-point hedonic scale with 1 and 9 representing “dislike extremely” and “like extremely,” respectively. Immediately after the panel, a elicitation mechanism auction method was used to obtain independent consumer willingness to pay for each aging time. Consumers were separated into 6 clusters based on overall acceptability ratings. Cluster 1 (n = 24) preferred steaks that were aged for 0 and 21 d (P ≤ 0.014). Cluster 2 (n = 50) liked all treatments moderately but liked steaks aged for 7, 14, and 21 d more than 0-d aged steaks (P ≤ 0.018); Cluster 3 (n = 20) preferred 0-d steaks over 7-d steaks and 7-d steaks over 14-d and 21-d aged steaks (P ≤ 0.044). Cluster 4 preferred 7-d and 21-d aged, and Cluster 6 preferred 14-d and 21-d aged steaks. Demand analysis indicated that 0, 7, and 21 d of aging would sell 5.29, 5.34, and 6.94 more units (0.454 kg) (P < 0.001) than steaks aged for 14-d holding price constant at the current market value of $14/0.454 kg. Overall, results indicated that wet aging for 14-d was not sufficient to provide the flavor and tenderness improvements that were apparent after 21 d of aging. Under optimal pricing and various cost scenarios, 21 d of aging was the most profitable single product offering only if daily production costs were sufficiently low.

Research on wet physical properties of permeable concrete pavement with different porosity

ABSTRACT Permeable concrete pavement has been widely used in building ‘sponge cities’. Porosity has a great influence on wet physical properties such as permeability, water retention, and evaporative cooling performance of permeable concrete, and further research is needed. In this paper, permeable concrete specimens with target porosity of 20%, 24%, and 28% were made for indoor experimental research, including water permeability, water retention, and evaporation tests. The research results show that permeable concrete with a porosity of 28% has the best permeability among the three types of porosity. In the range of 20–28% porosity, as the porosity increases, the water retention performance of permeable concrete first strengthens and then weakens. The evaporative water loss of permeable concrete has the worst cooling performance on its surface temperature and the best cooling performance on its internal temperature. The air humidity above permeable concrete continues to decrease over time. The greater the porosity of the specimen, the later the air humidity above it becomes lower than the indoor ambient humidity. The work of this paper provides data support for permeable concrete pavement to improve outdoor thermal environment.