Showing papers by "Kian Jon Chua published in 2021"
TL;DR: In this paper, the authors explored the fundamental link between the mixing efficiency and the entrainment performance for ensuring an efficient working of ejector in the associated energy systems, and their fundament links are clearly presented in a form of functional relation.
21 citations
TL;DR: In this article, the authors employed dimensional and scaling analysis (DASA) to unravel the key underlying relationships, leading to improved prediction and optimization of the SDHED's performance.
16 citations
TL;DR: In this paper, a novel building cooling system is proposed, which integrates dew point evaporative cooling, air-carrying energy radiant air conditioning and vacuum membrane-based dehumidification.
16 citations
TL;DR: In this paper, a novel ejector model with species transport is proposed that can clearly elucidate how, when, where and to what extent the two streams mix inside the steam ejector.
15 citations
TL;DR: In this article, the authors investigated the performance of a multistage coupled absorption chiller (ABC)-adsorption chiller cascade system, which is capable of producing potable water and three streams of chilled water under different temperature settings.
14 citations
TL;DR: In this paper, a dew-point evaporative cooler with counter-flow closed-loop configuration is proposed to achieve the simultaneous goals of pre-cooling, energy recovery and dehumidification.
11 citations
TL;DR: In this article, the transient behavior of a dew point evaporative cooler and its significant influence on the dynamic cooling performance was investigated, where a large time constant (400 s) of the product air temperature was observed under a zero-state response, leading to a pronounced deviation of the time-average cooling performance below its steady state.
10 citations
TL;DR: In this article, a multi-objective optimization model for a novel cascading quad-generation cold energy LNG recovery system is proposed to obtain the optimal operating parameters and component sizing, as well as corresponding performances for each condition.
8 citations
TL;DR: In this article, a coupled scaling and regression analysis is proposed as the key approach to link the physics-based model to fast data-driven optimization, which can accurately predict the experimental data of two coolers within 5.0% maximum discrepancy.
5 citations
01 Jan 2021
TL;DR: In this paper, composite superabsorbent polymers (SAPs) and metal-organic frameworks (MOFs) are presented for thermally driven dehumidification.
Abstract: The performance of desiccant-coated heat exchangers (DCHEs) strongly depends on the sorption and desorption characteristics of the employed desiccant material. While several attempts have been made to synthesize superior desiccants, the DCHE performance has not reached its highest potential due to challenges associated with the limited working capacity of the conventional pure/composite desiccants. This chapter presents two novel advanced desiccants, namely, composite superabsorbent polymers (SAPs) and metal-organic frameworks (MOFs). The composite SAPs offer superior sorption capacity, faster kinetics, and low regeneration possibility while the MOFs providing excellent hydrophilicity and tailorable structures. These desiccants are deemed to be the next generation of advanced materials in thermally driven dehumidifiers. Aside from documenting the characteristics of these new materials, a detailed list of experimental and theoretical material characterization studies is provided. Isotherms and kinetics are identified as key properties that fundamentally govern the desiccant’s performance in dehumidifiers, and relevant experimental and regression techniques to analyze them are also presented. In addition, the transient performance of the superabsorbent polymer DCHEs is compared and benchmarked against silica gel-coated heat exchangers. Lastly, results from a series of parametric experiments are presented by varying different operating parameters, and their sensitivity towards dehumidification capacity and thermal energy efficiency is estimated.
2 citations
01 Jan 2021
TL;DR: A comprehensive review of the state-of-the-art in desiccant coated heat exchangers can be found in this article, where the authors introduce the different types of isotherm and hysteresis profiles and specify the adsorption mechanisms.
Abstract: Desiccant coated heat exchangers (DCHEs) yield higher dehumidification and thermal efficiency over other solid desiccant dehumidifiers due to their effective removal of the exothermic heat of sorption and improved heat transfer effectiveness. Accordingly, they offer prospective energy and cost savings to several energy-related applications such as heat pumps, chillers, water harvesters, etc. A comprehensive review of the current state-of-the-art in DCHEs is imperative to understand this technology’s marked impact and its performing strategies and capabilities. This chapter first introduces the different types of isotherm and hysteresis profiles and specifies the adsorption mechanisms. Then it presents a list of conventional pure/composite desiccants employed and highlights their limitations. Next, the detailed steps involved during its binder material selection are presented, and a comparison is made between the different types of coating techniques. Different regeneration techniques are then described, and the relevance of thermal regeneration vis-a-vis microwave and ultrasonic methods is established. Lastly, the ideal characteristics of a desiccant are listed, which would pave the way for performance-enhancing synthesis of advanced desiccant materials.
01 Jan 2021
TL;DR: In this article, the authors presented a general mathematical approach to predict the performance of desiccant dehumidifiers based on the governing principles of mass, momentum, energy, and species conservation.
Abstract: In contrast to experimental testing, which is time-consuming and expensive, theoretical studies provide an economical and judicious methodology to evaluate the performance of desiccant dehumidifiers. Such approaches, developed based on the fundamental laws of thermodynamics, flow physics, and heat transfer, are critical to improving the dehumidifier design. This chapter firstly presents a general mathematical approach to predict the performance of DCHEs based on the governing principles of mass, momentum, energy, and species conservation. Next, the model is validated with the experimental results for different types of desiccants. Further, the validated model is employed to predict the performance of new fin-tube configurations. Detailed energy and economic analysis are then conducted on a hybrid central air-conditioning system comprising a composite superabsorbent polymer and mechanical vapor compression chillers. The hybrid configuration’s electrical power savings and its payback period are computed via this analysis. Lastly, the second law of thermodynamics is applied to study DCHEs and identify the causes of key irreversibility.
01 Jan 2021
TL;DR: In this article, the authors broadly discuss the future of cooling, highlight key sustainable alternative technologies, and comprehensively review the merits of solid desiccant dehumidification technologies.
Abstract: Population increase, rapid industrialization, economic growth, and increased demand for thermal comfort have exponentially raised buildings’ air-conditioning requirements. Over 90% of the current air-conditioning market is dominated by mechanical vapor compression (MVC) technology, which is essentially a coupled condensation dehumidification-cooling method. Its energy efficiency is low due to significant overcooling and reheating of the process air. In addition, its high electricity consumption contributes to substantial CO2-equivalent emissions and significantly impacts climate change. If the cooling demand continues to grow at the present rate, the MVC cooling technology will alone contribute to almost 0.5 °C rise in global temperatures by 2100s. Therefore, energy-efficient alternative cooling technologies are essential to address the sharp rise in building energy. Scientists worldwide are evolving new cooling technologies and have categorized them into solid-state, electrically driven mechanical, and thermally driven alternatives. Among the 20 alternatives that exist in different stages of research, prototyping, and commercialization, desiccant dehumidification technology decouples latent dehumidification and sensible cooling and has demonstrated to be an excellent solution to promote the energy efficiency of the conventional cooling process. This chapter broadly discusses the future of cooling, highlights key sustainable alternative technologies, and comprehensively reviews the merits of solid desiccant dehumidification technologies.