A heat recovery unit with phase change material for combi‐boilers

Abstract

A novel heat exchanger (HEX) with phase change material (PCM) is proposed to recover the waste heat from the flue gas of a combi‐boiler. The thermal energy that is recovered from the flue gas is stored within the PCM‐HEX when the combi‐boiler works in the central heating mode. The stored thermal energy is then released to pre‐heat the domestic water so that the combi‐boiler provides the domestic water at a required temperature more rapidly even in eco‐mode. A mathematical model is developed, and the discharging process of the PCM‐HEX is considered. The transient analyses are conducted to reveal the influences of the mass of PCM, the phase change temperature of the PCM, and the flow rate of the domestic water. It is found that the PCM‐HEX integrated combi‐boiler increases the domestic water temperature in the early period of the hot water demand. Results show that the water temperature increases as much as ΔT = 9.3°C and 19.2°C for the flow rates of 10 L/min and 3 L/min, respectively. Increasing the water temperature with the PCM‐HEX not only helps to reduce the waiting time of the end‐user but also improves the efficiency of the combi‐boiler and reduces the energy consumption.

Nanocellulose-based composite phase change materials for thermal energy storage: status and challenges

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Nano-engineered pathways for advanced thermal energy storage systems

“…3,75 Energy storage of recovered waste heat using PCMs has been used by numerous investigators to improve the efficiency of various systems. 76,77 In all of these examples, the underlying thermophysical properties and fundamental physical characteristics of the configuration (e.g., the location and number of nucleation sites) can significantly influence the overall performance of the PCMs in these applications.…”

Numerical analysis of phase change material filled with metal foam inside a cylindrical capsule

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