Improving dryer energy efficiency and controllability simultaneously by process modification

This work establishes a relationship between dryer energy performance and controllability using energy balances and process resiliency analysis. It is shown that using the process gain matrix, the dryer energy efficiency can be reliably calculated with conditions for simultaneous controllability improvement established. By incorporating a drying rate modifying system such as a desiccant dehumidifier as an add-on, these conditions are shown to be achievable due to the extra dehumidification which can be manipulated using the additional degrees of freedom introduced by the sorption system. Due to the adsorbent regulation properties which are enhanced by high-temperature regeneration, the resilience of energy performance to disturbances is significantly improved compared to conventional dryers. Also, a desiccant system performance indicator, the “adsorber–regenerator net energy efficiency ARNEE” is introduced and it is shown that energy efficiency improvement is possible only if the ARNEE is greater than the energy efficiency of the stand-alone dryer.     

Energy and exergy efficiencies as design criteria for grain dryers

We devised a novel methodology for optimizing cereal grain dryers grounded on the transient spatial–temporal first and second laws of thermodynamics and associated balance equations. Model equations were solved using a special time-adaptive radial basis function. Comprehensive sensitivity tests show the quantitative effects of initial moisture content, air velocity, and drying air temperature on the temporal profiles of outlet air temperature and moisture content and temporally integrated energy and exergy efficiencies. Drying temperature is the most efficacious parameter in the drying range of 50–90°C. Finally, selected examples show optimized dryer operation points under unrestrained and restrained conditions. Second law efficiency is well suited for expressing drying performance, portraying time, noble energy expenditure, and intrinsic sustainability. Three decision tables, based on simulation results, can be used to define dryer design under normal technical choice. First law efficiency and the specific moisture extraction rate are concepts more adequate for designing in-bin low-temperature dryers. Second law efficiency is indicated when exergy recuperation is at stake: higher drying temperatures, shorter drying times, recirculation drying, and other processes.     

Investigation on the Effect of Condensing Moisture before Heating Air on the Performance of a Batch Tray Dryer: Application to the Drying of Vanilla

This article presents the results of an investigation of the effect of pre-dehumidifying the drying air before it is heated and supplied into a batch tray dryer. Dehumidification is achieved through moisture condensation as the air flowing through a coil is cooled by chilled water from a cold source. As an example, this process is applied to the drying of vanilla and is based on a numerical method already validated by former results. Then, it is established through comparisons with a conventional batch tray dryer model that pre-dehumidification significantly reduces drying time. Furthermore, preheating air by an intermediate heating source reduces total energy consumption of the primary heating system to a level depending on the preset drying temperature. As regards batch tray dryer design and optimization purposes, these results open up particularly interesting heating and cooling sources utilization prospects.     

Investigation on the Effect of Condensing Moisture before Heating Air on the Performance of a Batch Tray Dryer: Application to the Drying of Vanilla

This article presents the results of an investigation of the effect of pre-dehumidifying the drying air before it is heated and supplied into a batch tray dryer. Dehumidification is achieved through moisture condensation as the air flowing through a coil is cooled by chilled water from a cold source. As an example, this process is applied to the drying of vanilla and is based on a numerical method already validated by former results. Then, it is established through comparisons with a conventional batch tray dryer model that pre-dehumidification significantly reduces drying time. Furthermore, preheating air by an intermediate heating source reduces total energy consumption of the primary heating system to a level depending on the preset drying temperature. As regards batch tray dryer design and optimization purposes, these results open up particularly interesting heating and cooling sources utilization prospects.     

Investigation on Drying Performance and Energy Savings of the Batch-Type Heat Pump Dryer

Simulation of the heat pump cycle and the drying process has been carried out to obtain the design parameters of the dryer. The analysis indicates that a specific moisture extraction rate (SMER) greater than 3.4 kg/kWh can be obtained. A box-type heat pump dryer has been developed and investigated for the performance of drying of shredded radish. Heat pump drying took 1.0–1.5 times longer than hot air drying. However, the heat pump dryer showed considerable improvement in energy savings. The SMER of the heat pump dryer was about three times higher than that of the hot air dryer.     

Energy and Cost Estimation for Application of Chemical Heat Pump Dryer to Industrial Ceramics Drying

Abstract

In this article we estimate the potential of a new chemical heat pump dryer (CHPD) application to an industrial ceramics drying process from the viewpoints of energy and cost saving. A CaSO₄/H₂O/CaSO₄·1/2H₂O hydration/dehydration CHPD system and a CaO/H₂O/Ca(OH)₂ hydration/dehydration CHPD system were examined. The CHPD systems store heat and simultaneously release the increased amount of heat at different temperature levels by using two chemical heat pumps (CHP) in their heat-enhancement mode. Furthermore, we propose enhanced systems using chemical heat pipes (CHPipe) for their environmental and cost merits. As a result, the consumed energy and the cost of using the CHPD systems in the industrial ceramics drying process are found to decrease to less than half of the conventional drying process using gas-fired boilers. For example, the energy efficiency and the cost of the present drying process are 28.4% and 604 × 10³ (JPY/month) (JPY: Japanese Yen), respectively. The energy efficiency and the cost of the proposed CHPD system are found to be 79.7% and 216 × 10³ (JPY/month), respectively, based on our experiments.     

Performance Study of a Closed-Type Heat Pump Tumble Dryer Using a Simulation Model and an Experimental Set-Up

In the interests of competitiveness, manufactures of tumble dryers are seeking to reduce both their electricity use and the drying time. This study examines how the cylinder volume of the compressor and the total heat transfer of the condenser influence the drying time and electricity use in a heat pump tumble dryer. A transient simulation model was developed and compared to an experimental set-up with good similarity. The simulations show that increasing the cylinder volume of the compressor by 50% decreases the drying time by 14% without using more electricity.     

A Critical Assessment of Industrial Coal Drying Technologies: Role of Energy,Emissions, Risk and Sustainability

Low-rank coals (LRCs) constitute about 45% of the total coal reserves and hence will soon be the fossil fuel of choice in many countries despite their high moisture content on mining, which varies from 30% to as high as 66%. It is important to reduce their water content to enhance the heating value and reduce transportation costs while enhancing combustion efficiency, safety, and reduction of emissions on combustion. The level of moisture to be achieved upon drying LRCs depends on the end application; it varies from as low as 0% for hydrogenation processes to 15% for briquetting and gasification processes. Numerous drying technologies have been proposed for drying coal; they include pulse combustion, vacuum, fluid bed, rotary, flash, microwave, and superheated steam drying. Each technology has some pros and cons, which are not always clearly spelled out in the literature. In addition, it is necessary to develop sustainable rather than just cost-effective drying systems for LRC. In this article we assess various coal drying techniques critically and identify their strengths and weaknesses. Some theoretical comparisons of different dryer types are carried out based on energy utilization and carbon footprints. The jury is still out on optimal drying technology for LRC and innovative design concepts should be evaluated before finalizing the selection.     

On Collective Molecular Dynamics in Biological Systems: A Review of Our Experimental Observations and Theoretical Modeling

We review processes by which different sounds, such as meditation music, mantra, kindness, or hatred expressions, and noises induce responses from cells and their components. We define ‘good’ or ‘bad’ sounds as those enhancing or inhibiting the cell’s biological activity, respectively. It is highlighted that the cellular dynamics results in a coherent organization with the formation of ordered patterns due to long-range correlations among the system constituents. Due to coherence, in the framework of quantum field theory, extended domains become independent of quantum fluctuations. Non-dissipative energy transfer on macromolecule chains is briefly discussed. Observed fractal features are analyzed by the fast Fourier transform and a linear relationship between logarithms of conjugate variables is observed. The fractal relation to the generation of forms (morphogenesis) and to the transition from form to form (metamorphosis) is commented. The review is also motivated by the suggestions coming from the cells’ responses, which show their ability to move from the syntactic level of the sound component frequencies to the semantic level of their collective envelope. The process by which sounds are selected to be good or bad sounds sheds some light on the problem of the construction of languages.