Cold Storage Capacity Research Articles

Improving C2H3Cl2F hydrate formation for cold storage in the presence of amino acids

The motivation of this study is to investigate the effect of side chain groups of amino acids on hydrate formation. To confirm their effects on hydrate nucleation and growth, we use aromatic amino acids (tryptophan, phenylalanine, tyrosine), heterocyclic amino acids (histidine, proline) and aliphatic acids (arginine, alanine) as biological additives. The effect of different side chain groups of amino acids on hydrate formation kinetics is investigated. It is found that the hydrophobic groups of amino acids have a significant influence on promoting hydrate formation compared with the hydrophilic groups. Among the hydrophobic groups, aromatic groups are superior to aliphatic groups in improving hydrate nucleation and growth rate, while aliphatic groups are more advantageous in increasing hydrate production, cold storage capacity (CSC) and hydrate conversion rate. Heterocyclic amino acids have no obvious effect on hydrate formation. In addition, foam is not produced during hydrate dissociation, which is good for practical application.

Performance regulation characteristics of bi-halide sorbents in the thermochemical sorption system for cold/heat storage

Thermochemical sorption is a promising technology for cold and heat storage. The performance regulation characteristics of bi-halide sorbents composed of CaCl2 and MnCl2 in different mixing ratios in the sorption energy storage system are investigated and compared by simulation and experiments in this paper. The simulation results show that the bi-halide sorbent can effectively reduce the reaction hysteresis temperature difference. The output energy becomes more concentrated, the start-up time is effectively shortened, and the stability of the energy output is ameliorated as the ratio of MnCl2 increases. Moreover, the experimental results corroborate the analysis in the simulation, and the maximum average cold and heat storage capacity of 2.7 kW and 1.6 kW, and their COP of 0.32 and 0.19 are obtained when the ratio of CaCl2 and MnCl2 is 6:1. In addition, the refrigerating power becomes concentrated in the early stage of the reaction with the mixing ratio of 1:3, and the time for rising to the average refrigerating capacity is significantly shortened from 900 s to 100 s. The consistency between simulation and experiments in the regulation characteristics illustrates that the bi-halide sorbent can improve the applicability of the sorption energy storage system in practical scenarios with different requirements.

Cooling and Power from Waste and Agriculture Residue as a Sustainable Strategy for Small Islands—A Case Study of Tonga

Identifying local energy sources and devising a circular economy could improve self-sufficiency in many Pacific Islands. On the islands with significant agriculture, the residue from the cultivation of plants has promising energy potential. The waste stream is another potential source of energy that otherwise should undergo proper treatment. Additionally, cold-storage capacity improves the preservation of crops and increases the agricultural exports of these islands. This study proposes a combined cooling and power (CCP) system driven by biomass from agriculture residue and waste streams as fuel for different districts in Tonga. The units supply a fraction of the districts’ electricity demand and provide sufficient cold-storage capacity to preserve the prospective yield of a fraction of fallow lands. The technical and economic performance of the CCP units was analysed for different fractions of electricity demand and fallow land exploitation in each district during a year of operation. The results show that the optimum combination of the CCP units supplies 38% of the total electricity demand of Tonga and prevents the annual consumption of 7.4 million litres of diesel and emission of 20 kilotonnes of CO2. In addition, it provides 3700 m2 of cold-storage area, which is sufficient for preserving the prospective yield of the exploitation of 27% of the total fallow land of Tonga. Annual export revenue of about AU$10 million is expected from such a cold-storage capacity for Tongan farmers. Furthermore, the units consume 10,000 tonnes of annual waste, significantly reducing waste management costs. This study presents an example of a comprehensive circular-economy solution for a remote island state that improves its socioeconomic and environmental condition by supplying the community’s local needs from its available and abundant resources under a viable business model. The solution presented in this study can be adapted to many island communities with significant agriculture in the economy and crucial energy and cooling needs.

SIMULASI DINAMIK PEMANFAATAN COLD STORAGE DI PELABUHAN PERIKANAN SAMUDERA BUNGU

Padang city precisely in the administrative area of ​​Labuhan Tarok Village, Teluk Kabung Bungus District, is a capture fish production center that makes a major contribution in West Sumatera, in that area already has a cold storage which is a facility belonging to the Ministry of Maritime affairs and fisheries. Currently, the cold storage is constrained by not being used optimally, where cold storage is often found in a condition less than 50% filled. Objective of this study was to analyze the utility level of the existing cold storage using a dynamic system. In this study primary data was used by the data collection methods, namely field observations, interviews, FGD and secondary data collection derived data from relevant government agencies. The software used in this research was Vensim software. Based on the dynamic simulation obtained, it was stated that the number of fish entering cold storage generally does not show significant fluctuations. By assuming the current fleet and fishing gear, it can be concluded that if we maintain the current condition of the vessels and fishing gear, the amounts of fish caught entering cold storage will still not get the optimal cold storage capacity. Therefore, it is necessary to disseminate information to the local fishing community to empower the use of cold storage, improve the facilities and infrastructure of ocean Bungus fishery port, especially cold storage, besides that it is hoped that the local government will help find subsidized assistance for more modern fishing fleets and gear. Keywords : cold storage, dynamic simulation, fish catch

Thermal performance analysis of multi-stage cold storage packed bed with modified phase change material based on Na2SO4·10H2O

Packed bed cold storage integrates a large number of phase change materials (PCMs) in a low-cost way, improves heat transfer performance by providing a larger heat transfer surface, and is considered a promising energy storage method in the field of air conditioning. However, PCM based on eutectic salt is often used for single-stage cold storage packed bed, which has poor cold storage performance and inferior stability. In this paper, the modified PCMs based on Na2SO4·10H2O with solidification temperatures of 5.11 °C, 7.06 °C, and 12.89 °C were proposed for multi-stage packed bed cold storage, and the formula of the material was modified and tested to improve the stability. The test showed that preheating before utilization can further reduce the subcooling degree caused by the freeze–thaw cycle. Through the CFD simulation of the established multi-stage packed bed model containing cylindrical encapsulated capsules, the cold storage capacity of a multi-stage packed bed with different PCMs filling ratios was compared. Results show that the cold storage density of the multi-stage packed bed with the filling ratio of 4:2:4 (PCM1:PCM2:PCM3) is 7.3 % higher than that of the single-stage packed bed, and the cold storage capacity can meet the emergency cooling demand of the air conditioner for at least one hour. This study provides a theoretical basis for the feasibility of the proposed modified eutectic salt PCM applied to multi-stage packed bed cold storage for air conditioning conditions.

Experimental Evaluation of the Effects of Passive Phase Change Material Walls on the Building Demand Response for Smart Grid Applications

Central air-conditioning systems play a significant role in the demand response (DR) strategies of buildings due to their high energy consumption and flexible energy use. Previous simulation-based studies have shown that the use of phase change materials (PCM) in building envelopes can substantially increase cold storage capacity, which is a key measure for improving the DR performance of buildings. In this study, we experimentally investigated the effect of passive PCM walls on DR performance and conducted quantitative experiments on factors affecting the precooling performance of PCM walls. During DR events, compared to Ordinary walls without a precooling and DR stage, passive PCM walls reduced room cooling loads by 75.05%, electricity consumption by 49.57%, and peak electricity consumption by 31.06%. Additionally, in the precooling period, the impact of the room precooling temperature on passive PCM precooling performance was experimentally studied. When the room precooling temperature was reduced gradually from 21.14 °C to 18.24 °C, the precooling period could be significantly shortened by between 14.58 and 40.43%, and the room cooling load firstly increased and then decreased, during which the cooling load reduction was up to 13.87%.

The Load Shifting Potential of Domestic Refrigerators in Smart Grids: A Comprehensive Review

Domestic refrigeration and freezing appliances can be used for electrical load shifting from peak to off-peak demand periods, thus allowing greater penetration of renewable energy sources (RES) and significantly contributing to the reduction of CO2 emissions. The full realization of this potential can be achieved with the synergistic combination of smart grid (SG) technologies and the application of phase-change materials (PCMs). Being permanently online, these ubiquitous appliances are available for the most advanced strategies of demand-side load management (DSLM), including real-time demand response (DR) and direct load control (DLC). PCMs are a very cost-effective means of significantly augmenting their cold storage capacity and, hence, their load-shifting capabilities. Yet, currently, refrigerators and freezers equipped with PCMs for DSLM are still absent in the market and research works focusing on the synergy of these technologies are still scarce. Intended for a multidisciplinary audience, this broad-scoped review surveys the literature to evaluate the technological feasibility, economic viability and global impact of this combination. The state-of-the-art of SG-enabling technologies is investigated—e.g., smart meters, Internet-of-Things (IoT)—as well as current and future standards and norms. The literature on the use of PCMs for latent heat/cold storage (LHCS) is also reviewed.

Prediction of ice making by vacuum flash evaporation with varying concentrations of MgCl2 solution

The study of ice slurry growth during vacuum ice production from salt solutions helps to gain a clear understanding of the crystallization characteristics of ice slurry. In this paper, the effects of different concentrations of MgCl2 solutions on the temperature, latent heat and thermal conductivity of ice slurry during vacuum ice production were investigated. It was shown that ice crystal formation during vacuum ice production undergoes four stages: flash boiling, subcooling, ice crystal nucleation and the ice slurry generation stage. Morphological changes in the ice crystal formation process of salt solutions were visualized. It was also noticed that the addition of MgCl2 facilitated the refinement of ice crystals. Moreover, the relationship between concentration and latent heat and between concentration and thermal conductivity was established eventually by fitting the experimental data with polynomials. The fitted curves do not exceed 2% error from the experimental data. In practical vacuum ice production applications, the mathematical relationships obtained from this paper are of great importance for adjusting the concentration of the salt solution to meet the requirements of the corresponding cold storage capacity.

Polyurethane foam based composite phase change microcapsules with reinforced thermal conductivity for cold energy storage

The purpose of this research is to develop a new type of core/wall material reinforced microcapsules by in-situ polymerization, which is applied to polyurethane foam (PUF) to prepared composite materials for cold chain transportation. The core material of MEPCMs was C12, modified with Nano-CuO; the wall material was Melamine-Formaldehyde (MF), modified with Carbon nanotubes (CNTs). The comprehensive performances of MEPCMs and composite materials were measured by SEM, FT-IR, XRD, DSC, LFA, and TGA. The results indicated that the addition of CNTs or Nano-CuO has almost no effect on the spherical structure of the MEPCMs, and the thermal conductivity increased 108% compared to the ordinary MEPCMs. The modified microcapsules also showed excellent cycling stability and thermal stability. Microencapsulated phase change materials (MEPCMs) helped PUF to form uniform and dense cells, and the cell structure became denser with the increasing content of MEPCMs. The cold storage capacity of the composite materials with 10.3 wt% MEPCMs was 83% higher than ordinary PUF.

Solidification of an annular finned tube ice storage unit

Increasing building energy consumption rates is leading to significant surcharges for both the peak grid loads and the peak building energy consumption costs. The power load mismatches between user demands and energy supplies can be effectively reduced by ice storage systems. In order to solve the problem of heat transfer attenuation in the cold storage process. This study used a two-dimensional axisymmetric transient model of an annular finned tube ice storage unit to investigate the solidification characteristics and heat transfer rates with water as the storage medium and ethylene glycol as the heat transfer medium. The model was validated against experimental data. The calculations then investigated the effect of the annular fin height and fin spacing on the phase change and the solidification front velocity. The results show that increasing the fin height and decreasing the fin spacing both increase the ice storage solidification rate and improve the cold storage capacity. At a fin height of 50 mm, its solid phase fraction was 4.96 times larger than that of the bare tube. The cold storage capacity with the 50 mm high fins is more than 3.68 times that without fins at 480 min. The 4 mm fin spacing has a 26.3% greater cold storage capacity than the 12 mm fin spacing.

Investigation on the dynamic adsorption characteristics of activated carbon to Helium-4 for 4-20 K regenerator of cryocoolers

With the advantages of long life and high reliability, cryocoolers gradually substitute cryogenic liquids to become a critical guarantee for the stable operation in space exploration. For cryocoolers, the regenerator is a key component that strongly influences its refrigeration performance. The specific heat of current commonly-used regenerator materials below 20 K is significantly lower than that of the working gas Helium-4, resulting in insufficient cold storage capacity of the regenerator and further limiting the cryocooler’s ability to obtain lower temperatures and larger cooling capacity. In this paper, activated carbon is used to absorb a part of helium in the regenerator to replace the traditional magnetic regenerator materials. By establishing a low-temperature dynamic adsorption model, the dynamic adsorption characteristics of activated carbon to Helium-4 in the temperature range of 4-20 K were studied, and the effect of its microscopic adsorption/desorption heat effect on the performance of the regenerator was investigated.

Experimental study on the preparation and cool storage performance of a phase change micro-capsule cold storage material

In this paper, a cold storage air conditioning system based on a phase change micro-capsule material was constructed. The appropriate micro-encapsulated phase change materials were selected according to the temperature of the generator and evaporator. In addition, phase change materials were encapsulated and mixed with water with good thermal conductivity to form phase change micro-capsule suspensions, which takes into account the latent heat, fluidity and thermal conductivity of the phase change. Three kinds of micro-capsule phase change material suspensions with good stability and mass fractions of 5%, 10% and 15% were prepared. The main thermophysical parameters of the suspensions were obtained by analysis. In addition, the cold storage characteristics of the phase change micro-capsule suspensions in the cold storage tank of the composite system were experimentally studied. The results showed that the best composition ratio of base liquid was 99.1% deionized water, 0.2% SDS, 0.2% xanthan gum, and 0.5% NaCl. At the same cold storage time, compared with the evaporation temperature of −5 °C, when the evaporation temperature was −10 °C, the cooling capacity of the system decreased significantly. The cold storage capacity of phase change cold storage was approximately 1.5 times higher than that of ice cold storage, and the overall performance of phase change cold storage was better than that of ice cold storage. The developed phase change micro-capsule suspension has been considered to have some effect on phase change cold storage.

Coupling relationship between cold chain logistics and economic development: A investigation from China.

This paper builds an evaluation index system, uses the entropy weight method (EWM) to decide the weights and, based on the coupling coordination degree model (CCDM), it systematically studies the coupling relationship between Chinese cold chain logistics and the Chinese economy from 2010 to 2019. It performs a grey relational analysis (GRE) to explore the main factors influencing the coordinated development of the two. The results show that the coupling coordination degree between the two presents a steady upward trend, and their coupling relationship has been upgraded from 'coordination' to 'good coordination'. They also indicate that the added value in the tertiary industry, the per capita gross domestic product (GDP), and household consumption levels are the main factors affecting the development of cold chain logistics, while the per capita cold storage capacity, the turnover of road cold chain freight, and the volume of human-power employed in cold chain logistics are the main factors affecting economic development. This study makes suggestions to support the coordinated development of cold chain logistics and economy, and provides a scientific basis for further research.

Dynamic melting of encapsulated PCM in various geometries driven by natural convection of surrounding air: A modelling-based parametric study

Encapsulated phase change material (PCM) has a great potential to reduce the fluctuation of indoor air temperature and subsequent building energy consumption through ceiling applications in air-conditioning systems. However, the effects of capsule geometry on the dynamic melting performance remain unknown when the melting is driven by natural convection. In this work, we modelled the melting behavior of PCM encapsulated in six different capsule shapes subject to natural convection of surrounding air, which was validated by our measurement results. The model considers the conjugate heat transfer through the surrounding air, capsule shell and PCM, enabling the prediction of a three-stage dynamic melting process. The melting process of the encapsulated PCM were further studied for varying inclination angles (with respect to the vertical axis), temperature differences (between the surrounding air and PCM), and capsule sizes. The results show that the capsule geometry plays a dramatic role in the time of phase change. At the ambient temperature of 22°C, the short cylindrical capsule with a horizontal axis takes the longest time to complete phase change (162 min), whilst the pyramidal capsule with a horizontal base takes the shortest time (120 min). We also quantified the heat transfer between capsules and surrounding air for varying temperature difference and capsule size, and found that the pyramidal and tetrahedral capsules with a horizontal base melt faster than capsules of other shapes due to the higher heat transfer rate caused by larger surface area. For cases with a medium capsule size and low temperature difference, early termination of melting at 80% liquid fraction is recommended since more than 30% of melting time can be saved with only 20% reduction in cold storage capacity. This work provides a validated model that is able to predict the dynamic melting process of PCM of different geometries, which will enable informed design of PCM panels for improving thermal management and comfort in buildings.

A new hybrid cold storage material

Transportation of biological samples, such as cryopreserved mammalian cells, at ultra-low temperature, has been critical for medical research and services. The general public has now recognized another vital role of ultra-low temperature transport due to its irreplaceable role in delivering various vaccines that can protect us from deadly viruses. This study focuses on the cold storage material to facilitate the low-temperature transportation of vaccines and other commodities such as seafood. Dry ice does not suffice for the long-range transport of these products to rural areas. We propose using a combination of dry ice and ethanol, which has a higher thermal capacity, thermal conductivity, and latent heat, to produce a much more sustainable cooling solid for an extended period of cold transportation. We performed a detailed analysis of the performance of this new cold solid material to examine the feasibility of using it for shipping vaccines. The calculations showed that the new substance’s cold storage capacity is 47.6 percent higher than dry ice. Therefore, this new combined substance is more appropriate for ultra-low temperature transportation. It is a promising new cold storage technology. Furthermore, the unique cold storage material combination presents a more economical and environmentally friendly transport cooling solution.

Solidification performance enhancement of encapsulated ice storage system by fins and copper foam

It is critical for the encapsulated ice storage system to maintain high cooling capacity within permissible time. In this paper, the strengthening effects of metal foam and fins on ice storage spheres are numerically studied comprehensively. The variations of the temperature field, ice front evolution, solidification fraction, total solidification time and the cold storage capacity are analyzed under four different strengthening configurations (plain, fins, metal foam and metal foam composite fins). The optimum porosity is obtained after the comparison of four comprehensive criteria about the input-output performance. Finally, the dimensionless parameters of the metal foam ice storage sphere are analyzed. The results demonstrate that the temperature distribution in the metal foam ice storage sphere is more uniform, and the solidification rate is faster due to coupled effects of thermal conduction enhancement and the suppression of the natural convection. Metal foam composite fins can remarkably save 83.5% of the solidification time and enhance the solidification rate by 6.1 times compared with the non-enhancement case. Dimensional analysis of the results is presented as the solidification fractions versus an appropriate combination of the porosity, Fourier, and Stefan numbers. Compared with the previous non-metal foam prediction formula, the formula reported in this research is more accurate. The prediction accuracy can improve by 20%.

Role of copper foam on solidification performance of ice-cool storage sphere system

Due to the poor thermal conductivity of phase change material (PCM), the application of the ice-cool storage sphere system is hindered. In this paper, the solidification performance of heat transfer after adding copper foam to the ice-cool storage sphere system is numerically studied by Computational Fluid Dynamic (CFD). The enthalpy-porosity method is used to describe the PCM solidification. Local thermal equilibrium is numerically adopted for modeling the heat transfer between the PCM and the solid matrix in copper foam. The variations of temperature field, ice front evolutions, solidification fraction, total solidification time, and cold storage capacity are investigated with the consideration of natural convection. The influence of surface temperature is explored by Stefan (Ste) number. A new evaluation index is proposed that can evaluate the cold storage performance of the energy storage system in real-time. The results show the metal foam focuses on accelerating the upper heat transfer due to the influence of natural convection in the plain ice storage sphere. The total ice storage time can be reduced by at least 72.7% in copper foam ice storage sphere with the porosity of 0.97, at the cost of very little ice storage capacity reduction. A higher porosity of copper foam is recommended with a compromise on the total melting time. This paper provides a clear and comprehensive vision of the metal foam effects of different temperatures and porosity inside the ice-cool storage sphere systems.

Enhancement of hydrate formation with amino acids as promoters

Environmentally friendly amino acids are reported as promising kinetic accelerators for hydrate formation. In this work, the effect of three amino acids (valine, leucine and methionine) with aliphatic side chains on the kinetics of HCFC-141b hydrate formation under static conditions is studied. These amino acids have different hydrophobicity. There is an optimal addition amount to promote hydrate formation for each amino acid. Leucine with moderate hydrophobicity has the best promoting effect on hydrate nucleation. It can be inferred that the hydrophobic group of amino acid affects hydrate formation, and there is an optimal hydrophobicity range. It is also found that the valine, which has the higher hydrophobicity, is more beneficial to increase the cold storage capacity of HCFC-141b hydrate. HCFC-141b hydrate nucleation has a stochastic nature and the additive of valine, leucine or methionine reduces the scatter of hydrate induction time.

A class II MHC-targeted vaccine elicits immunity against SARS-CoV-2 and its variants

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in over 100 million infections and millions of deaths. Effective vaccines remain the best hope of curtailing SARS-CoV-2 transmission, morbidity, and mortality. The vaccines in current use require cold storage and sophisticated manufacturing capacity, which complicates their distribution, especially in less developed countries. We report the development of a candidate SARS-CoV-2 vaccine that is purely protein based and directly targets antigen-presenting cells. It consists of the SARS-CoV-2 Spike receptor-binding domain (SpikeRBD) fused to an alpaca-derived nanobody that recognizes class II major histocompatibility complex antigens (VHHMHCII). This vaccine elicits robust humoral and cellular immunity against SARS-CoV-2 and its variants. Both young and aged mice immunized with two doses of VHHMHCII-SpikeRBD elicit high-titer binding and neutralizing antibodies. Immunization also induces strong cellular immunity, including a robust CD8 T cell response. VHHMHCII-SpikeRBD is stable for at least 7 d at room temperature and can be lyophilized without loss of efficacy.

Dynamic performance analysis of a solar driving absorption chiller integrated with absorption thermal energy storage

The use of a solar-powered absorption chiller for residential cooling is impeded by the instability and intermittency of solar energy with time. Integrating the absorption heat storage into the absorption refrigeration alleviates the mismatch between solar sources and the cold demand. This paper investigated a solar-powered absorption chiller with an absorption thermal energy storage system using a dynamic numerical model. The dynamic model is solved according to the nonlinear programming and the second-order iterative numerical integration program. Based on simulation and comparison results, the performance characteristics for the proposed system are discussed. The results indicate that the combination of an absorption chiller and absorption thermal energy storage is feasible. Compared with the reference system, the total refrigerating capacity and average performance coefficient for the proposed system are increased by 4.44% and 3.5%. Finally, the total cold storage capacity of the integrated system can reach 6890.4 MJ/day, which can extend the cooling time to about 14 h. This research provides insight into future work regarding the wide application for solar cooling.