Search Results (13)

Highlighting waste as a wealth is the future sustainability of the world. Also, using solar energy stored during off-sun periods will overcome the energy crisis. The introduction of wood chip waste for thermal energy storage systems is a sustainable opportunity. Cellulose derived from wood chips was mixed with the environmentally benign magnetite to form a composite (WCM) and mixed with paraffin-based PCM. The composite was characterized through transmission electron microscopy, TEM analysis, scanning electron microscopy, SEM (augmented with dispersive X-ray analysis, EDX). Micrographs, Fourier transform infrared (FTIR), and X-ray diffraction (XRD), which confirmed that the composite material was prepared. Various system proportions of the composite (0.5, 1.0, 2.0, and 4.0%) are embedded in paraffin, and then the thermal system performance is compared. The experimental data revealed that the addition of 2.0 weight percent of composite material showed superior system performance. Also, differential scanning calorimeter (DSC) and TEM analyses of the paraffin-based WCM-composite materials are conducted. The system achieved a heat gain of 87 kJ/min in comparison to 7 kJ/min for 2.0% WCM-PCM and pristine PCM, respectively. Hence, WCM-PCM embedded with waste stream nanoparticles could be suggested as a potential candidate for heating applications. Full article

In this paper, we describe DECAL, a prototype Monolithic Active Pixel Sensor (MAPS) device designed to demonstrate the feasibility of both digital calorimetry and reconfigurability in ASICs for particle physics. The goal of this architecture is to help reduce the development and manufacturing costs of detectors for future colliders by developing a chip that can operate both as a digital silicon calorimeter and a tracking chip. The prototype sensor consists of a matrix of 64 × 64 55 $\mathsf{\mu }$m pixels, and provides a readout at 40 MHz of the number of particles which have struck the matrix in the preceding 25 ns. It can be configured to report this as a total sum across the sensor (equivalent to the pad of an analogue calorimeter) or the sum per column (equivalent to a traditional strip detector). The design and operation of the sensor are described, and the results of chip characterisation are reported and compared to simulations. Full article

The non-isothermal crystallization behaviors of poly (ethylene glycol) (PEG) and poly (ethylene glycol)-b-poly(ε-caprolactone) (PEG-PCL) were investigated through a commercially available chip-calorimeter Flash DSC2+. The non-isothermal crystallization data under different cooling rates were analyzed by the Ozawa model, modified Avrami model, and Mo model. The results of the non-isothermal crystallization showed that the PCL block crystallized first, followed by the crystallization of the PEG block when the cooling rate was 50–200 K/s. However, only the PEG block can crystallize when the cooling rate is 300–600 K/s. The crystallization of PEG-PCL is completely inhibited when the cooling rate is 1000 K/s. The modified Avrami and Ozawa models were found to describe the non-isothermal crystallization processes well. The growth methods of PEG and PEG-PCL are both three-dimensional spherulitic growth. The Mo model shows that the crystallization rate of PEG is greater than that of PEG-PCL. Full article

Ultrafast chip nanocalorimetry opens up remarkable possibilities in materials science by allowing samples to be cooled and heated at extremely high rates. Due to heat transfer limitations, controlled ultrafast cooling and heating can only be achieved for tiny samples in calorimeters with a micron-thick membrane. Even if ultrafast heating can be controlled under quasi-adiabatic conditions, ultrafast controlled cooling can be performed if the calorimetric cell is located in a heat-conducting gas. It was found that the maximum possible cooling rate increases as $1/r_0$ with decreasing radius $r_0$ of the hot zone of the membrane. The possibility of increasing the maximum cooling rate with decreasing $r_0$ was successfully implemented in many experiments. In this regard, it is interesting to answer the question: what is the maximum possible cooling rate in such experiments if $r_0$ tends to zero? Indeed, on submicron scales, the mean free path of gas molecules $l_{mfp}$ becomes comparable to $r_0$, and the temperature jump that exists at the membrane/gas interface becomes significant. Considering the limitation associated with thermal resistance at the membrane/gas interface and considering the transfer of heat through the membrane, we show that the controlled cooling rate can reach billions of K/s, up to 10¹⁰ K/s. Full article

In this study, a Sn–Bi composite solder paste with thermosetting epoxy (TSEP Sn–Bi) was prepared by mixing Sn–Bi solder powder, flux, and epoxy system. The melting characteristics of the Sn–Bi solder alloy and the curing reaction of the epoxy system were measured by differential scanning calorimeter (DSC). A reflow profile was optimized based on the Sn–Bi reflow profile, and the Organic Solderability Preservative (OSP) Cu pad mounted 0603 chip resistor was chosen to reflow soldering and to prepare samples of the corresponding joint. The high temperature and humidity reliability of the solder joints at 85 °C/85% RH (Relative Humidity) for 1000 h and the thermal cycle reliability of the solder joints from −40 °C to 125 °C for 1000 cycles were investigated. Compared to the Sn–Bi solder joint, the TSEP Sn–Bi solder joints had increased reliability. The microstructure observation shows that the epoxy resin curing process did not affect the transformation of the microstructure. The shear force of the TSEP Sn–Bi solder joints after 1000 cycles of thermal cycling test was 1.23–1.35 times higher than the Sn–Bi solder joint and after 1000 h of temperature and humidity tests was 1.14–1.27 times higher than the Sn–Bi solder joint. The fracture analysis indicated that the cured cover layer could still have a mechanical reinforcement to the TSEP Sn–Bi solder joints after these reliability tests. Full article

By using an atomic force microscope (AFM) coupled to a fast scanning chip calorimeter (FSC), AFM-tip induced crystal nucleation/crystallization in poly (ε-caprolactone) (PCL) has been studied at low melt-supercooling, that is, at a temperature typically not assessable for melt-crystallization studies. Nanogram-sized PCL was placed on the active/heatable area of the FSC chip, melted, and then rapidly cooled to 330 K, which is 13 K below the equilibrium melting temperature. Subsequent isothermal crystallization at this temperature was initiated by a soft-tapping AFM-tip nucleation event. Crystallization starting at such surface nucleus led to formation of a single spherulite within the FSC sample, as concluded from the radial symmetry of the observed morphology. The observed growth rate in the sub-micron thin FSC sample, nucleated at its surface, was found being much higher than in the case of bulk crystallization, emphasizing a different growth mechanism. Moreover, distinct banding/ring-like structures are observed, with the band period being less than 1 µm. After crystallization, the sample was melted for gaining information about the achieved crystallinity and the temperature range of melting, both being similar compared to much slower bulk crystallization at the same temperature but for a much longer time. Full article

The non-isothermal crystallization kinetics of double-crystallizable poly(ethylene glycol)–poly(l-lactide) diblock copolymer (PEG-PLLA) and poly(ethylene glycol) homopolymer (PEG) were studied using the fast cooling rate provided by a Fast-Scan Chip-Calorimeter (FSC). The experimental data were analyzed by the Ozawa method and the Kissinger equation. Additionally, the total crystallization rate was represented by crystallization half time t_1/2. The Ozawa method is a perfect success because secondary crystallization is inhibited by using fast cooling rate. The first crystallized PLLA block provides nucleation sites for the crystallization of PEG block and thus promotes the crystallization of the PEG block, which can be regarded as heterogeneous nucleation to a certain extent, while the method of the PEG block and PLLA block crystallized together corresponds to a one-dimensional growth, which reflects that there is a certain separation between the crystallization regions of the PLLA block and PEG block. Although crystallization of the PLLA block provides heterogeneous nucleation conditions for PEG block to a certain extent, it does not shorten the time of the whole crystallization process because of the complexity of the whole crystallization process including nucleation and growth. Full article

A spark plug calorimeter is introduced for quantifying the thermal energy delivered to unreactive gas surrounding the spark gap during spark ignition. Unlike other calorimeters, which measure the small pressure rise of the gas above the relatively high gauge pressure or relative to an internal reference, the present calorimeter measured the differential rise in pressure relative to the initial pressure in the calorimeter chamber. By using a large portion of the dynamic range of the chip-based pressure sensor, a high signal to noise ratio is possible; this can be advantageous, particularly for high initial pressures. Using this calorimeter, a parametric study was carried out, measuring the thermal energy deposition in the gas and the electrical-to-thermal energy conversion efficiency over a larger range of initial pressures than has been carried out previously (1–24 bar absolute at 298 K). The spark plug and inductive ignition circuit used gave arc-type rather than glow-type discharges. A standard resistor-type automotive spark plug was tested. The effects of spark gap distance (0.3–1.5 mm) and ignition dwell time (2–6 ms) were studied for an inductive-type ignition system. It was found that energy deposition to the gas (nitrogen) and the electrical-to-thermal energy conversion efficiency increased strongly with increasing gas pressure and spark gap distance. For the same ignition hardware and operating conditions, the thermal energy delivered to the gap varied from less than 1 mJ at 1 atm pressure and a gap distance of 0.3 mm to over 25 mJ at a pressure of 24 bar and a gap distance of 1.5 mm. For gas densities that might be representative of those in an engine at the time of ignition, the electrical-to-thermal energy conversion efficiencies ranged from approximately 3% at low pressures (4 bar) and small gap (0.3 mm) to as much as 40% at the highest pressure of 24 bar and with a gap of 1.5 mm. Full article

A chip-based fast scanning calorimeter (FSC) is used as a fast hot-stage in an atomic force microscope (AFM). This way, the morphology of materials with a resolution from micrometers to nanometers after fast thermal treatments becomes accessible. An FSC can treat the sample isothermally or at heating and cooling rates up to 1 MK/s. The short response time of the FSC in the order of milliseconds enables rapid changes from scanning to isothermal modes and vice versa. Additionally, FSC provides crystallization/melting curves of the sample just imaged by AFM. We describe a combined AFM-FSC device, where the AFM sample holder is replaced by the FSC chip-sensor. The sample can be repeatedly annealed at pre-defined temperatures and times and the AFM images can be taken from exactly the same spot of the sample. The AFM-FSC combination is used for the investigation of crystallization of polyamide 66 (PA 66), poly(ether ether ketone) (PEEK), poly(butylene terephthalate) (PBT) and poly(ε-caprolactone) (PCL). Full article

In order to ensure the safety of inflammable and explosive chemical substance such as nitrocellulose (NC) mixtures in the process of handing, storage, and usage, it is necessary to obtain the fire properties of NC with different exterior structures. In present study, fire properties of two commonly used nitrocelluloses with soft fiber structure and white chip structure were investigated by scanning electron microscope (SEM) and the ISO 5660 cone calorimeter. Experimental findings revealed that the most important fire properties such as ignition time, mass loss rate and ash content exhibited significant differences between the two structures of NC. Compared with the soft fiber NC, chip NC possesses a lower fire hazard, and its heat release rate intensity (HRRI) is mainly affected by the sample mass. In addition, oxygen consumption (OC) calorimetry method was compared with thermal chemistry (TC) method based on stoichiometry for HRRI calculation. HRRI results of NC with two structures obtained by these two methods showed a good consistency. Full article

Thermal sensors based on thermopiles are some of the most robust and popular temperature sensing technologies across industries and research disciplines. A chip calorimeter with a 3D thermopile layout with a large sensing area and multichannel capacity has been developed, which is highly desired for many applications requiring large reaction chambers or high throughputs, such as biofilm research, drug screening, etc. The performance of the device, including temperature sensitivity and heat power sensitivity, was evaluated. The capability to split the chip calorimeter to multiple channels was also demonstrated, which makes the chip calorimeter very flexible and powerful in many applications. Full article

We set out to determine the particle-size distribution, the fiber, the bark and the leaves content, the heating value, the CNH and the ash content of a wide sample of wood chips, collected from 10 forestry and 10 agroforestry production sources. This sampling focused on two main production types: forestry (Full Tree System—FTS—and logging residues—LR) and agroforestry (Short Rotation Coppice—SRC). For the forestry production wood chips from coniferous and broadleaf species were considered. For the agroforestry production wood chips from poplar plantations were examined (different clones with two different harvesting intervals). Overall, we collected 400 samples. Particle size distribution was determined with an automatic screening device on 200 samples. The higher heating value was determined on 200 subsamples using an adiabatic bomb calorimeter. The CNH and the ash content was ascertained on another 200 subsamples. FTS and SRC (with three year old sprouts) offered the best quality, with high fiber content (71%–80%), favorable particle-size distribution and good energetic parameters. On the contrary, both logging residues and SRC (with two year old sprouts) presented a high bark content (18%–27%) and occasionally a mediocre particle-size distribution, being often too rich in fines (6%–12%), but the energetic parameters are in the normal range. Full article

Various recently proposed biomass fuels are reviewed from the point of view of their safety. Many biomass materials are proposed for use as fuels, such as refuse derived fuel (RDF), wood chips, coal-wood mixtures, etc. However, these fuels have high energy potentials and can cause fires and explosions. We have experienced many such incidents. It is very difficult to extinguish fires in huge piles of biomass fuel or storage facilities. Here current studies on heat generation for these materials and proposed evaluation methods for these new developing materials in Japan are introduced, which are consistent with measurements using highly sensitive calorimeters such as C80, or TAM, and gas emission tests. The highly sensitive calorimeters can detect small heat generation between room temperature and 80 °C, due to fermentation or other causes. This heat generation sometimes initiates real fires, and also produces combustible gases which can explode if fuel is stored in silos or indoor storage facilities. Full article