Tingting Zhu

University of Twente | UT · Faculty of Engineering Technology (CTW)

The performance improvement of flat-plate solar air collectors (FPSACs) is vital for solar energy utilization. Accordingly, flat micro heat pipe arrays (FMHPAs) have been utilized to FPSACs given their excellent thermal conductivity and suitable specific surface area. To investigate the impact of structural parameters of the flat-plate solar air co...

An air-source heat pump simulation model, accounting for evaporator and condenser pressure drop, has been developed. The model is capable of computing the heat pump's coefficient of performance (COP) under different ambient temperatures and relative humidities above frosting conditions. This research extends an existing iterative simulation method...

The binary refrigerant mixtures containing 2,3,3,3-Tetrafluoroprop-1-ene are considered as excellent substitutes for traditional refrigerants. Weak hydrogen bonds exist in hydrofluorocarbons and hydrofluoroolefins. However, for several recently published binary refrigerant mixtures, there is no Vapor–Liquid Equilibrium calculation study considering...

Lithium-ion batteries, the heart of electric vehicles (EVs), are subject to capacity attenuation and lithium plating at low temperatures, which is essential to preheat lithium-ion batteries at low-temperature ambient. In this study, a battery thermal management system (BTMS) was established to achieve integration of preheating and cooling at the mo...

Performance prediction of cold thermal energy storage (CTES) devices is an important step in guiding their design and application. However, related studies are limited, and some do not consider the influence of structural parameters. In this study, a CTES with metal foam–composite phase-change materials (PCMs) was built, and the influence mechanism...

Latent heat storage technology is a valuable research direction to alleviate the imbalance of energy supply and demand, but its application is limited by the low thermal conductivity of phase change material. In recent years, the fin–foam structure is proven to alleviate this problem. The solidification behavior of the phase change material in this...

Developing hybrid electric aircraft is propitious to reducing carbon dioxide emissions and fuel consumption. Combustion engines coupled with solid oxide fuel cells are proposed for aircraft propulsion systems, where the compressor is powered by fuel cells instead of turbines. The thermal cycle of the new engine is obviously different from that of c...

A solar air collector (SAC) is a main device of a solar-thermal air system, which can absorb solar radiation and transfer the absorbed thermal energy to the air. This paper presents a systematic review of three basic types of SAC, namely, the flat-plate SAC (FPSAC), the evacuated tube SAC (EVTSAC), and the concentrated SAC. High efficiency, low hea...

The ambition of zero emission neighborhood has been set out to operate the building components with zero life cycle greenhouse gas emissions. Hydrocarbon heat pumps as the building components with nearly zero greenhouse gas emissions are faced with the problem of simultaneously reducing refrigerant charges and maintaining competitive capacities. Th...

Polymer electrolyte membrane fuel cell is a clean and promising energy device in the near future; the present work proposes newly designed baffle plates that feature unequal height and space distance arrangements in the cathode flow field of fuel cells. Using a three dimensions multiphase fuel cell model, the effects of various newly designed baffl...

A novel split type vacuum tube (VT) solar air thermal collection-stepped storage system (ST-VTSATC-SSS) is proposed in this study to address the problem of carbon and pollution emissions from coal-fired heating in rural areas. A VT air collector is used to decrease heat loss. Paraffin and lauric acid are used to conduct thermal stepped storage. The...

Employing booster heat pumps (BHP) in district heating systems can provide a way to use low temperature heat sources for district heating as they allow locally increasing the water temperature on the user side where necessary. Thereby, it can provide decreased heat loss of a district heating system. This experimental study investigated steady state...

As the main source of heat loss of flat-plate solar air collectors (FPSACs), single glazing cover reduces the thermal performance of FPSAC. This situation becomes serious when the ambient temperature is low or the inlet temperature is high. A double glass cover with good thermal insulation is a good solution. This work aims to investigate the therm...

Understanding of droplet dynamic characteristics on gas diffusion layer (GDL) of polymer electrolyte membrane (PEM) fuel cell is of great importance for cell performance improvement. This study comprehensively investigated droplet dynamic characteristics on fuel cell cathode GDL with gradient pore size distribution (GPSD). The influence of differen...

Solar air heater is a simple and convenient technology to utilize solar thermal energy. In this paper, an optimization study was carried out for a micro-heat pipe arrays-based solar air heater, aiming to derive the optimal operation conditions and geometrical parameters of the solar air heater. A 3-D CFD model was developed based on the physical he...

In this paper, the potential of expander speed regulation for optimization of ORC system adaptability to off-design working conditions has been explored through experiments. According to the obtained results, it has been found that there existed two different optimal speeds: optimal power speed (rop), optimal efficiency speed (roee/rote) which coul...

The collector–storage solar air heating system has huge application potential in many fields. Traditional collector–storage solar air heating systems have been applied in related fields, but improving the temperature of phase change materials (PCMs) quickly is difficult because these systems are open. On the basis of a literature review, this study...

A thermal storage unit (TSU) with flat microheat pipe arrays (FMHPAs) as heat transfer core is experimentally investigated in this study. A comprehensive evaluation parameter of the TSU defined as thermal power intensity is proposed. The effects of the length proportion of the air side and the phase-change material (PCM) side on the heat transfer p...

This study investigated the performance of an integrated collector storage solar air heater based on latent heat storage and flat micro-heat pipe arrays. The structure and working principle of the device were explained in detail. The effective area of the collector is 0.93 m², and the mass of the phase change material (PCM) is 45.8 kg. An integrate...

In this study, a comparative investigation of two types of microheat pipe array (MHPA) flat-plate solar air collectors (FPSAC) based on exergy analysis has been conducted. The thermal performance of MHPA-type solar air collectors (SACs) with two different shaped fins is experimentally evaluated. A detailed parametric study is also conducted to exam...

An experimental latent-thermal energy storage device (LTESD) with a flat miniature heat pipe array (FMHPA) as a core heat transfer element is designed. Multihole flat pipes are utilized as a heat supply and heat removal loop for the passage of heat transfer fluid (HTF). Experiments are performed at different HTF volume flow rates and inlet temperat...

Heat recovery significantly and positively affects energy conservation and prevents global warming. A small flat heat pipe heat recovery device (SFHPHRD), which applies flat micro-heat pipe array (FMHPA) with welded, serrated and staggered fin on its surface, is designed as a core heat transfer component in the heat recovery systems of residential...

In this study, the performance of an integrated collector storage solar air heater based on flat micro-heat pipe arrays (FMHPA) was investigated. The structure and working principle of the device were explained in detail. Using the micro-heat pipe array as the key heat-transfer part and the 52 # paraffin wax as the phase change material (PCM), The...

This paper proposes a new type of a flat-plate solar air collector (SAC) with micro-heat pipe arrays (MHPA), which consist of a heat collection and transfer section and an air ventilation and heat exchange section. In the unique structure, the heat exchange of air is separated from heat collection and transmission. This work experimentally and theo...

An experimental energy storage system was designed using a new-type flat micro-heat pipe heat exchanger that incorporates a moderate-temperature phase-change material paraffin with a melting point of 58 °C. The basic structure, working principles, and design concept were discussed. The heat-transfer process during the charging and discharging of th...

In common types of flat-plate solar air heaters, the uneven flow and heat exchange between air and an absorber plate poses a problem. To resolve this problem, this paper proposed a novel type of flat-plate solar air heater based on micro-heat pipe arrays (MHPA). An investigation was carried out on the design, thermal performance and flow resistance...

The thermal performance of an air-based latent thermal storage unit is analyzed and discussed in this study. The thermal storage unit uses flat micro-heat pipe array (FMHPA) as the core heat transfer component and lauric acid as phase change material (PCM). An experimental system is constructed to test the heat storage-release property of the stora...

An investigation on the design, thermal performance (time constant and efficiency) and flow resistance characteristic of a novel type of CPC (Compound Parabolic Concentrator) solar air collector by using flat micro-heat pipe arrays (FMHPA) was carried out theoretically and experimentally. Instantaneous efficiency and flow resistance curves are obta...

Abstract In this study, the heat transfer characteristics of a new-type flat micro-heat pipe thermal storage unit, which uses a moderate-temperature paraffin as heat storage phase change material, were investigated. The basic structure, working principle, and design concept of the thermal storage unit were discussed. Experiments were conducted to s...

This paper presents a novel flat plate solar water heater (SWH) using micro heat pipe array (MHPA) sprayed solar selective coating and arranged closely as the absorber of collector. The collector has the advantage of resistance to freezing, high heat transfer ability, relatively low heat loss, elimination of welding, and prevention of leakage. The...

A novel type of solar air collector by using flat heat pipe arrays was designed. The relationship between the heat collecting performance and the air flow rate at different seasons was investigated experimentally. The flow resistance of the solar collector was also studied. The experimental results showed that the heat collecting efficiency of the...