This paper reviews the development of latent heat thermal energy storage systems studied detailing various phase change materials (PCMs) investigated over the last three decades, the heat transfer and enhancement techniques employed in PCMs to effectively charge and discharge latent heat energy and the formulation of the phase change problem. It also examines the geometry and configurations of PCM containers and a series of numerical and experimental tests undertaken to assess the effects of parameters such as the inlet temperature and the mass flow rate of the heat transfer fluid (HTF). It is concluded that most of the phase change problems have been carried out at temperature ranges between 0 °C and 60 °C suitable for domestic heating applications. In terms of problem formulation, the common approach has been the use of enthalpy formulation. Heat transfer in the phase change problem was previously formulated using pure conduction approach but the problem has moved to a different level of complexity with added convection in the melt being accounted for. There is no standard method (such as British Standards or EU standards) developed to test for PCMs, making it difficult for comparison to be made to assess the suitability of PCMs to particular applications. A unified platform such as British Standards, EU standards needs to be developed to ensure same or similar procedure and analysis (performance curves) to allow comparison and knowledge gained from one test to be applied to another.

A review of materials, heat transfer and phase change problem formulation for latent heat thermal energy storage systems (LHTESS)

Phase change materials for thermal energy storage

Review on sustainable thermal energy storage technologies, Part I: heat storage materials and techniques

http://www.celsius.co.kr/phase_change_materials/download/energy/Phase_Change_Materials_for_Smart_Textiles.pdf

Phase change materials for smart textiles – An overview

In the rapidly developing shale gas industry, managing produced water is a major challenge for maintaining the profitability of shale gas extraction while protecting public health and the environment. We review the current state of practice for produced water management across the United States and discuss the interrelated regulatory, infrastructure, and economic drivers for produced water reuse. Within this framework, we examine the Marcellus shale play, a region in the eastern United States where produced water is currently reused without desalination. In the Marcellus region, and in other shale plays worldwide with similar constraints, contraction of current reuse opportunities within the shale gas industry and growing restrictions on produced water disposal will provide strong incentives for produced water desalination for reuse outside the industry. The most challenging scenarios for the selection of desalination for reuse over other management strategies will be those involving high-salinity produced water, which must be desalinated with thermal separation processes. We explore desalination technologies for treatment of high-salinity shale gas produced water, and we critically review mechanical vapor compression (MVC), membrane distillation (MD), and forward osmosis (FO) as the technologies best suited for desalination of high-salinity produced water for reuse outside the shale gas industry. The advantages and challenges of applying MVC, MD, and FO technologies to produced water desalination are discussed, and directions for future research and development are identified. We find that desalination for reuse of produced water is technically feasible and can be economically relevant. However, because produced water management is primarily an economic decision, expanding desalination for reuse is dependent on process and material improvements to reduce capital and operating costs.

/pdf/desalination-and-reuse-of-high-salinity-shale-gas-produced-31vn27zkft.pdf

Desalination and reuse of high-salinity shale gas produced water: drivers, technologies, and future directions

Analysis of single-effect evaporator desalination systems combined with vapor compression heat pumps

Multi-effect boiling systems from an energy viewpoint

A performance analysis is presented for the vapour compression parallel feed multiple effect evaporation water desalination system. The systems include mechanical (MVC) and thermal (TVC) vapour compression. The system models take into account the dependence of the stream physical properties on temperature and salinity, thermodynamic losses, temperature depression in the vapour stream caused by pressure losses and non-condensable gases, flashing within the effects, and the presence of flashing boxes. The analysis is performed as a function of the brine distribution configuration (parallel or parallel/cross flow), the top brine temperature, the temperature of the brine blowdown, and the temperature difference of the compressed vapour condensate and the brine blowdown. The analysis is focused on variations in the parameters that control the product cost, which includes the specific heat transfer area, the thermal performance ratio, the specific power consumption, the conversion ratio, and the specific flow rate of the cooling water. Results show consistent behaviour with industrial practice, where the thermal performance ratio of the TVC system decreases at higher top brine temperatures, while the specific power consumption of the MVC systems decreases at higher temperatures. Also, the specific heat transfer area for all configurations decreases at higher operating temperatures. The conversion ratio is found to depend on the brine flow configuration and to be independent of the vapour compression mode. For the parallel flow configuration, the conversion ratio decreases with the increase of the operating temperature. On the other hand, the conversion ratio for the parallel/cross flow system decreases with the increase of the brine blowdown temperature. Predictions of both models show good agreement with field data.

Multiple Effect Evaporation—Vapour Compression Desalination Processes

Effectiveness of a thermal energy storage system using phase-change materials

The paper describes a theoretical investigation for the steady-state counter flow wet cooling tower with modified definitions for both the number of transfer units and the tower thermal effectiveness. The modified number of transfer units is dependent on both air and water heat capacity. The effectiveness is defined by the tower cooling range and the approach to equilibrium. A new expression relating the tower effectiveness to the modified number of transfer units and the capacity rate ratio has been developed. The model considered the resistance to heat transfer in the water film, the nonunity of the Lewis number, and the curvature of the saturated air enthalpy curve. A procedure for implementing the model in designing or rating cooling towers has been outlined and demonstrated through illustrative examples. The model compares very satisfactorily with other methods such as Logarithmic Mean Enthalpy Difference (LMED) and conventional effectiveness-NTU. Within the ranges used, the obtained results showed that substantial errors varied from +4.289 to -2.536 percent can occur in calculating the cooled water outlet temperature, and errors from +42.847 to -16.667 percent can occur in estimating the tower thermal characteristics.

Faisal Al-Juwayhel

Papers

Analysis of single-effect evaporator desalination systems combined with vapor compression heat pumps

Multi-effect boiling systems from an energy viewpoint

Multiple Effect Evaporation—Vapour Compression Desalination Processes

Effectiveness of a thermal energy storage system using phase-change materials

A Modified Analysis of Counter Flow Wet Cooling Towers