Continuous Heating Mode Research Articles

A study of capacity demands for heat pumps intermittent heating of China’s residences

Heat pump heating is one of the most promising solutions for transitioning residential heating in China’s cold regions, as well as hot summer and cold winter regions from centralized, continuous heating to decentralized, intermittent heating, promoting low-carbon transformation. However, the fundamental issue of the actual capacity requirements for heat pumps in intermittent heating has not yet been addressed. In view of this, this study developed a numerical model that considers the dynamic coupling characteristics between the heat pump and the building environment. Using the model, the worst startup conditions for heat pumps in intermittent heating, actual heat pump capacity demands, and the differences in capacity compared to continuous heating mode for residential buildings in 230 Chinese cities are analyzed. The findings revealed an exponential relationship between intermittent heating capacity demands and time constraints, as well as a linear relationship with heating temperature. Specifically, the impact of the set temperature on capacity demands in cold regions and hot summer and cold winter regions is 22.8 W/(m2·°C) and 32 W/(m2·°C), respectively. These findings provide insights into the planning and design of future intermittent heating renovation projects in China.

Impact of heating strategies towards energy-efficient buildings

Mitigating climate change and its impact requires intensive efforts to reduce greenhouse gas emissions, transition to renewable energy sources, and implement sustainable practices. Intermittent heating is considered a sustainable and effective way to achieve energy savings compared with continuous heating mode. However, recent studies have found that energy savings from intermittent heating depend on several factors, namely the building envelope solution. Therefore, this work intends to fill the research gap by comparing the energy efficiency and thermal performance of different construction systems, using two real-scale test cells, one built with a Light Steel Framing (LSF) solution and the other with concrete and Hollow Brick Masonry (HBM) solution. An experimental monitoring campaign was performed during the heating season, aimed at analysing the energy consumption, the responsiveness of the test cells to the heating system, and the influence of the outdoor climate on energy consumption, considering different heating strategies (intermittent patterns and continuous). In general, the LSF test cell registered lower energy consumption when compared to the HBM test cell. However, the LSF test cell presented significant fluctuations of the indoor temperature, confirming that it is more susceptible to the outdoor climate conditions. This research concluded that a system with lower thermal inertia has superior energy saving potential.

Studies on selective laser quenching by high repetition frequency lasers with scanning galvanometer

This study introduces a novel material processing methodology termed High Repetition Frequency Selective Laser Quenching (HRF-SLQ). This technique utilizes high-power lasers with a maximum power of 5 kW in conjunction with a scanning galvanometer, operating at elevated repetition rates up to 200 Hz, to specifically treat surfaces of high and medium carbon steels. The application of this method leads to the creation of allotropic metal matrix composite materials (A-MMCs). In general, the scanning speed of a galvanometer can range from hundreds to thousands of times per second. Based on the high acceleration and rapid jumping characteristics of the scanning galvanometer, this technology transforms the high-power laser heating of metal plates from continuous heating mode to parallel pulse heating mode, which repeats heating 30 to 200 times per second. This transformation ensures the quenched layer avoids melting even under prolonged irradiation times by high-power lasers. Consequently, it can significantly enhance processing efficiency by selective laser quenching (SLQ), ensuring that the depth of the hardened layer reaches 0.88–0.94 mm and keeping the surface smooth without melting. This paper systematically investigates the influence of various processing parameters, such as laser power (P), single heating time (t1), and the number of processing units (N), on the depth of the SLQ and the quenching efficiency. It also examines the impact of HRF-SLQ technology on the properties of A-MMCs and analyzes temperature field variations from room temperature to melting point through simulation methods combined with laser quenching experiments.

An Enhanced Electro-Thermal Coupled Model With Lithium Plating Detection for Lithium-Ion Battery at Low Temperatures

Lithium plating may occur when lithium-ion batteries are charged at a high current rate and low ambient temperature. As a result, the battery degradation is accelerated and the risk of thermal runaway is increased. Along these lines, an enhanced electro-thermal model was proposed in this work for charging at low temperature values. By considering the battery with a reference electrode, a dual RC model was built. The developed model can predict the anode potential to prevent the lithium plating. The thermal model and absolute state of charge (SOC) were integrated into the battery model to solve the SOC inconsistency caused by the battery temperature rise during the charging process. Then, the proposed electro-thermal model was used to predict the electrical and thermal characteristics of a 50 Ah battery under various charging rates and low ambient temperature values conditions. In addition, the prediction results were validated by the experiment data. The maximum errors of the cathode potential and battery terminal voltage were 0.058 V and 0.154 V, respectively, whereas the maximum cell temperature error was 0.88 °C. Based on the anode prediction electro-thermal coupling model, a segmented heating strategy without lithium plating was proposed to describe the fast battery charging procedure, which can reduce energy consumption by 16.1% and save charging time by nearly 10 minutes compared with the continuous high-power heating mode.

A simulation study on the heating characteristics of residential buildings using intermittent heating in Hot-Summer/Cold-Winter areas of China

Radiant air conditioning system is an important heating method with better thermal comfort, less noise and greater energy-saving potential. However, different intermittent heating modes may significantly impact both the heating efficiency and indoor thermal comfort, which has been neglected in existing studies. Therefore, to obtain optimal intermittent heating modes for achieving higher energy efficiency and better indoor thermal comfort for the residential buildings in Hot Summer and Cold Winter areas, a TRNSYS model of the radiant air conditioning system was developed and validated. The indoor thermal comfort and energy consumption characteristics during the coldest day and entire heating season were simulated and analyzed based on four different intermittent heating modes. The results demonstrated that the supply water temperature of the air source heat pump unit and the radiant terminals stabilized at the set temperature in about 1 h during the start-up stage, and the indoor air temperature stabilized at 24.0 °C after 7.5 h during the shutdown stage. The proportion of time that meets first-level thermal comfort under the four intermittent heating modes was above 90.1% and even higher at over 96.1% when considering the sleeping period. Compared to the continuous heating mode, the four intermittent heating modes saved 22.3%, 25.8%, 40.4% and 48.4% of energy. Overall, the preferred intermittent heating mode for residential buildings with the radiant air conditioning system in Hot Summer and Cold Winter areas was identified as switching on from 7:00 to 15:00 and 19:00 to 3:00, while switching off from 15:00 to 19:00 and 3:00 to 7:00. This model not only considered the immediate benefits of improved indoor thermal comfort and energy efficiency, but also showed great advantages in developing sustainable construction.

Boosting Electrical Response toward Trace Volatile Organic Compounds Molecules via Pulsed Temperature Modulation of Pt Anchored WO3 Chemiresistor.

Insufficient limit of detection (LoD) toward volatile organic compounds (VOCs) hinders the promising applications of metal oxide chemiresistors in emerging air quality monitoring and/or breath analysis. There is an inherent limitation of widely adopted strategies of creating sensitive chemiresistors then operating at the optimized temperature via a continuous heating (CH) mode. Herein, a strategy combining Pt single atoms anchoring (chemical sensitization) with pulsed temperature modulation (PTM, physical sensitization) is proposed. Apart from generating abundant surface asymmetric oxygen vacancy (Pt-VO -W) active sites at pulsed high temperature (HT) stage, inward diffusion of trace target VOCs across the sensing layer at pulsed low temperature stage (driven by PTM induced concentration gradient), can greatly enhance the charge interaction probability between the generated surface active species and the surrounding VOCs, and thus offers a novel avenue on addressing the bottleneck issue of low LoD by PTM. Triggered by HT of 300°C, the responses of Pt anchored WO3 chemiresistor to 1 ppm trimethylamine (TMA) and xylene can be drastically boosted from 1.9(CH) to 6541.5 (PTM) and 1.5 (CH) to 1001.1 (PTM), respectively. And ultra-low theoretic LoD of 0.78 ppt (TMA) and 0.18 ppt (xylene) are successfully achieved, respectively.

Microheater Integrated Nanotube Array Gas Sensor for Parts-Per-Trillion Level Gas Detection and Single Sensor-Based Gas Discrimination.

Real-time monitoring of health threatening gases for chemical safety and human health protection requires detection and discrimination of trace gases with proper gas sensors. In many applications, costly, bulky, and power-hungry devices, normally employing optical gas sensors and electrochemical gas sensors, are used for this purpose. Using a single miniature low-power semiconductor gas sensor to achieve this goal is hardly possible, mostly due to its selectivity issue. Herein, we report a dual-mode microheater integrated nanotube array gas sensor (MINA sensor). The MINA sensor can detect hydrogen, acetone, toluene, and formaldehyde with the lowest measured limits of detection (LODs) as 40 parts-per-trillion (ppt) and the theoretical LODs of ∼7 ppt, under the continuous heating (CH) mode, owing to the nanotubular architecture with large sensing area and excellent surface catalytic activity. Intriguingly, unlike the conventional electronic noses that use arrays of gas sensors for gas discrimination, we discovered that when driven by the pulse heating (PH) mode, a single MINA sensor possesses discrimination capability of multiple gases through a transient feature extraction method. These above features of our MINA sensors make them highly attractive for distributed low-power sensor networks and battery-powered mobile sensing systems for chemical/environmental safety and healthcare applications.

In-situ Observation of Retained Austenite and Residual Stress Evolutions during Tempering of carbonitrided DIN 1.6587 Alloy Steel

This paper investigates the evolution of retained austenite and residual stresses during and after tempering of carbonitrided 18CrNiMo7-6 low alloy steel carried out using in-situ X-ray diffraction technique. In this case, two carbonitriding treatments with different surface the retained austenite contents of 20 and 54 mass.-% are investigated. The tempering is carried out in a continuous heating mode to 650°C as well as in isothermal mode at holding temperature of 170, 240, and 300°C for 2 hours. During continuous heating at a heating rate of 10°C/min, the retained austenite started to decompose at 290°C. On isothermal holding at 170°C for 2 hours, the retained austenite remained relatively stable at 20 and 54 mass.-% while readily decomposed to less than 5 mass-% on holding at 300°C. On continuous heating, residual stress in martensite continuously relaxes and reaches full relaxation (0 MPa) at about 400°C. During isothermal holding, residual stresses in martensite are increasingly relaxed with increasing holding tempering. Further relaxation of residual stresses is observed during cooling whereas a cyclic variation of the residual stresses in the retained austenite could be determined.
 Keywords: Carbonitriding, retained austenite, residual stresses, tempering, in-situ XRD
 This paper investigates the evolution of retained austenite and residual stresses during and after tempering of carbonitrided 18CrNiMo7-6 low alloy steel carried out using in-situ X-ray diffraction technique. In this case, two carbonitriding treatments with different surface the retained austenite contents of 20 and 54 mass.-% are investigated. The tempering is carried out in a continuous heating mode to 650°C as well as in isothermal mode at holding temperature of 170, 240, and 300°C for 2 hours. During continuous heating at a heating rate of 10°C/min, the retained austenite started to decompose at 290°C. On isothermal holding at 170°C for 2 hours, the retained austenite remained relatively stable at 20 and 54 mass.-% while readily decomposed to less than 5 mass-% on holding at 300°C. On continuous heating, residual stress in martensite continuously relaxes and reaches full relaxation (0 MPa) at about 400°C. During isothermal holding, residual stresses in martensite are increasingly relaxed with increasing holding tempering. Further relaxation of residual stresses is observed during cooling whereas a cyclic variation of the residual stresses in the retained austenite could be determined.

Microwave-assisted high-efficient gas production of depressurization-induced methane hydrate exploitation

To provide solution for the high-efficient gas production from hydrate deposits, the microwave-assisted depressurization method is proposed, and its feasibility is numerically demonstrated. Through systematically analyzing the effects of microwave parameters, phase components, and porous media properties, we found that microwave heating can provide timely and sufficient energy for hydrate dissociation, and the energy efficiency of microwave heating can be relatively high in the condition of high initial water saturation, high initial hydrate saturation, low specific heat capacity, high thermal conductivity, high porosity, and low absolute permeability. In addition, the microwave heating operational strategy is evaluated and optimized to achieve the high energy efficiency and rapid gas production, which demonstrating that the one-cycle continuous heating mode has the best performance on promoting hydrate dissociation. Compared to the typical heating case, the energy efficiency and gas generation efficiency in the optimized one-cycle continuous heating case are enhanced by 20.73% and 23.14%, respectively. The findings of this study contribute to the understanding of gas production behavior of depressurization induced hydrate dissociation assisted by microwave heating, which can provide some insights for evaluating and optimizing the methodology for gas production from gas hydrate reservoirs.

Indoor thermal environment of kindergarten building: A case study in China

Based on the building of a kindergarten in Weinan, Shaanxi Province, this paper explores the influence of different envelope structures and heating modes on the indoor thermal environment for the energy saving and thermal comfort of the existing buildings. Using operating temperature as the evaluation index of thermal comfort, the 15 designed schemes were simulated through Energyplus software and actual measurement to obtain the operating temperature change law and annual heating energy consumption value. The envelope structure optimized by choosing energy-saving building materials such as expansion perlite and foam cement is obviously conducive to the improvement of indoor thermal comfort, and the thickness of the insulation layer increases, and the operating temperature increases accordingly; Although the standard effective temperature in intermittent heating mode is slightly lower than that in continuous heating mode, the standard effective temperature rises significantly with the extension of preheating time, which can meet the requirements of thermal comfort.After energy saving transformation, the total heating energy consumption of the kindergarten building is reduced by up to 3644 GJ, and the energy-saving rate reaches 67%.

Accelerating gas production of the depressurization-induced natural gas hydrate by electrical heating

Natural gas hydrate (NGH) will be one of the major future energy sources due to its properties of clean energy and large reserves. Depressurization is proposed as an effective method to extract natural gas from hydrate, however, the gas production from hydrate dissociation may be interrupted by ice generation and hydrate re-formation due to insufficient heat supply in the single depressurization process. To solve this issue, this work conducted simulation on accelerating gas production from the depressurization-induced methane hydrate by electrical heating. The continuous heating and intermittent heating modes were employed and then the electrical heating scheme was optimized for the comprehensive effect of high energy efficiency and high gas production rate. The results show that electrical heating is conducive to gas production from hydrate dissociation at a rapid rate. In the continuous heating, a high initial hydration saturation, low initial water saturation, low specific heat capacity, and high thermal conductivity result in the high gas generation rate and efficient electrical energy utilization (a large energy efficiency ratio). The intermittent heating has a higher efficient utilization of electrical energy than continuous heating. The optimal scheme is determined as the first-half heating type with the optimized electrical heating power of 25.6 W and the heating time of 12.5 min by the gradient descent method of AdaGrad. Compared to the baseline continuous heating case, the energy efficiency ratio (10.70) of the optimal scheme is enhanced by 24.7% with the average gas production rate (2.55 SmL/s) enhanced by 18.2%. It's hoped that the findings of this work can provide some insights into extracting natural gas from gas hydrate deposits. Electrical heating is employed to provide heat for the endothermic dissociation of methane hydrate induced by depressurization for accelerating natural gas production in this work. The electrical heating scheme is optimized to achieve high-efficient utilization of electrical energy for the fast extraction of natural gas from hydrate dissociation. • Electrical heating accelerates the depressurization induced dissociation of hydrate. • The effects of phase components and porous media properties are analyzed. • Intermittent heating has higher efficiency of energy utilization than continuous heating. • The electrical heating power is optimized by the gradient descent method of AdaGrad. • The optimal scheme is first-half heating with the optimized electrical heating power.

An oil shale recovery system powered by solar thermal energy

The oil shale in-situ recovery requires huge thermal energy, which has become one of the important factors restricting its further development. Using solar thermal energy for oil shale in-situ recovery is thought to be an environmental friendly way to solve the problem. In this paper, an in-situ solar thermal shale oil recovery system with rated output power of 100 MW is analyzed as a study case to understand its cost-effectiveness. The correlation between oil shale production cost (PC) and the solar multiple (SM), the thermal energy storage (TES) capacity and the distance between injection well and production well (Dw) is studied. The result shows that, when the SM is 2.5, TES capacity is 16 h, and Dw is 20 m, the PC of oil shale in-situ recovery with solar intermittent heating mode is the lowest, which is 306 $/t and is even lower than that with continuous heating mode by natural gas and natural gas-assisted solar energy. Besides, the sensitivity analysis shows that the cost of O&M has the biggest effect on the PC. However, due to the high initial cost of the solar field, when the discount rate is above 8.23%, oil shale in-situ recovery by solar energy intermittent heating is uneconomical.

Applicability of thermal dissipation probe in the determination of trunk flow of Platycladus orientalis under cyclic heating mode

To evaluate the adaptability of the cyclic heating mode in the thermal diffusion probe method (TDP) in the measurement of trunk sap flow and the accuracy of the measurement of tree transpiration water consumption, we selected Platycladus orientalis as the research object and set three different heating modes: 60 min/0 min (continuous heating mode), 30 min/30 min (cyclic heating mode with 30 min heating and 30 min cooling), 10 min/50 min (cyclic heating mode with 10 min heating and 50 min cooling). Based on the measured value of the whole tree container wei-ghing method, the temperature gradient characteristics of different heating modes were analyzed using the measurement technology of thermal diffusive trunk sap flow. The Granier's corrected formulas of cyclic heating modes were constructed, with its error being analyzed by validity verification. The results showed that sap flow rate calculated by the cyclic heating mode was consistent with the diurnal variation of the transpiration rate measured by the whole tree weighing method. The temperature of cyclic heating mode could quickly rise, fall and performed stably. The sap flow calculated by Granier's original formula was 61.3% lower than that by weighing method. The corrected Granier formula in the mode of 10 min/50 min and 30 min/30 min were Fd=0.0177K0.9457 (R2=0.88) and Fd=0.0378K1.3146(R2=0.85), respectively. The difference of sap flow rate in P. orientalis by the new formula was smaller than that measured by the whole tree weighing method, and the error of transpiration rate calculated by the 10 min/50 min correction formula was the smallest, 5.9% lower than that calculated by the weighing method, and thus could express the real flow rate. The 10 min/50 min cyclic heating mode could be used to reduce the effect of natural temperature difference, cut down power consumption, and accurately reflect the actual sap flow rate of P. orientalis.

Peculiarities of Pulsed Heating by the Radiation of a Subterathertz Gyrotron in the Production of Metal Oxide Nanopowders

The peculiarities of the process of preparation of metal oxide nanopowders by the evaporation–condensation method with pulsed heating of the material by focused subterahertz radiation are described. It is shown experimentally that the optimal conditions for the rapid evaporation of a substance are achieved at the highest possible pulse power and the largest possible duty cycle at a fixed average power. Under these conditions, it is possible to heat and evaporate the substance with a focused radiation beam in a relatively short time, so that the adjacent layers of the evaporated substance are not warmed and fused and a relatively low thermal conductivity is maintained. A linear increase in the evaporation rate with an increase in the duty cycle of the heating pulses is revealed, and this increase reaches the fivefold value relative to the continuous heating mode.

Ammonia sensors based on resistive structures M–SnO2:Sb–M

The paper presents a comparison of the responses of sensors to ammonia in continuous heating and thermal cycling modes, and also shows the dependence of the response time of the sensors on the content NH3. Thin films of tin dioxide were obtained using RF magnetron sputtering, and then annealed in air at a temperature of 425°C for 24 hours. In thermal cycling, the temperature of the heating cycle remains constant 400 °C (duration of the heating cycle was 8 s). The temperature of the cooling cycle changes in the range 200 °C – 100 °C, but duration of cooling of the cooling cycle was remained constant of 5 s. It was shown that the thermal cycling mode has several advantages over the constant heating mode. The experiments showed that sensors based on SnO2:Sb have short response times – less than 3 seconds.

Real-time chemical analysis of root filling materials with heating: guidelines for safe temperature levels.

To investigate the chemical changes affecting different types of gutta-percha and endodontic sealers during heating, and correlate changes with the heating capacity of different heat carriers. The heating capacity of three endodontic heat carriers was evaluated using thermocouples to produce heat profiles. The devices were activated at different temperature set-ups, in continuous or cut-out modes. Chemical changes of six brands of gutta-percha and four types of sealers were assessed in real time during heating using micro-Raman spectroscopy equipped with a heating stage. Raman spectra of each tested material were averaged and compared at different temperature levels. The sealers were further assessed by Fourier transform infrared (FT-IR) spectroscopy. None of the tested heat carriers achieved the temperature levels that were set by the devices and recommended by the manufacturer. The use of continuous heating mode resulted in higher rises in temperature than the 4s cut-out mode that reached 110°C. The various brands of gutta-percha exhibited different chemical changes in response to heat. Some changes even occurred below temperature levels generated by the heating devices. All sealers revealed changes in their chemical composition upon heating. Changes in epoxy resin- and zinc oxide-eugenol-based sealers were detectable at 100°C, with structural alterations beyond that temperature and irreversible changes after cooling. Water loss was irreversible in BioRoot, but its chemical structure was stable as well as for the TotalFill. The heating capacity of endodontic heat carriers needs to be standardized, so that the temperatures delivered by the tips are the same as that set on the dial. Practitioners should be aware of the actual temperatures generated by these devices, and the suitability of sealers to be used at the temperature levels achieved.

Comparative study on the annual performance between loop thermosyphon solar water heating system and conventional solar water heating system

Loop thermosyphon (LT) is usually introduced to overcome the freezing and corrosion problems associated with the conventional solar water heating (SWH) system. Compared with the conventional SWH system, the LT-SWH system possesses a lower nighttime heat loss because of the thermal diode property of loop thermpsyphon but bigger daytime heat loss because of the secondary heat exchange. However, the effect of above interaction to the system performance is rarely reported based on long-term running. In this study, based on the typical meteorological year data of Fuzhou city, annual performances of above two systems, including the effective number of supplying days, effective heat gain and nighttime heat loss, are comparatively analyzed under two different operational modes. Variations of above mentioned variables with the increment in the set temperature are discussed. The results indicate that, under the discontinuous heating mode, the effective numbers of supplying days of SWH system and LT-SWH system are 139 and 153, respectively. While the numbers of days are respectively 168 and 173 under the continuous heating mode. The SWH system possesses an expected bigger nighttime heat loss ratio with an average annual value of 15.07% corresponding to 6.15% for the LT-SWH system. Particularly, for the LT-SWH system, the different relative magnitudes of heat loss coefficients functioning at different times leads to a smaller temperature drop at night and also a smaller temperature rise at the subsequent day. It generates an unanticipated results that corresponds to the same month from November to April, the two systems have the approximate effective heat gain. The set temperature significantly influences the relative magnitudes of annual effective number of supplying days and annual effective heat gain, the superiority of LT-SWH system gradually diminishes and even reverses with the increment in the set temperature. The bigger daytime heat loss dominating the dominance is responsible for that transition. Combining with a longer static payback period, it is conditional to substitute the conventional SWH system with the LT-SWH system, especially when the water temperature on demand is high.

Особенности импульсного нагрева излучением субтерагерцевого гиротрона при получении нанопорошков оксидов металлов

The paper describes the features of the metal oxide nanopowder obtaining by an evaporation-condensation method with pulsed heating of the material by focused subterahertz radiation. It has been experimentally shown that optimal conditions for the rapid evaporation of a substance are achieved at the highest possible pulse power and the lowest possible duty cycle at a fixed average power. Under these conditions, it is possible to realize the heating and evaporation of a substance in a focused radiation beam in a relatively short time, while the adjacent layers of the substance maintain a relatively low thermal conductivity. A linear increase in the evaporation rate with a decrease in the duty cycle of heating pulses was demonstrated, the increase reached 5 times relative to the continuous heating mode.

CFD Analysis of a Buffer Tank Redesigned with a Thermosyphon Concentrator Tube

This study analyzes a buffer tank simulated in both continuous operation mode and heating mode using CFD techniques. The analysis is focused in the thermal behavior of the tank, especially in parameters such as heat exchanged, heating time, and temperature distributions into the tank, in order to propose a better design. The results of the different simulations show that the tank heats water extremely slowly and extremely evenly when producing domestic hot water (DHW), which negatively affects the thermal stratification that is critical for rapidly reaching the DHW temperature. Therefore, the main problem of the tank is an inefficient heat exchange and a poor distribution of temperature. In order to overcome these operational limitations, a new design is proposed by installing a tube inside the tank that encloses the heating coil and sends hot water directly to the tank top region such that high-temperature DHW is rapidly provided, and thermal stratification is improved. Several simulations are performed with different open and closed configurations for the outlets of the inner tube. The different results show that the heating times significantly improve, and the time needed to reach the 45 °C set point temperature is reduced from 44 to 15 min. In addition, the simulations in which the opening and closing of the water outlets are regulated, the outlet DHW temperature is kept within 45–60 °C, which prevents overheating to unsafe use temperatures. Furthermore, the results of the simulation in continuous operation mode show a clear improvement of thermal stratification and an increase in the heat transmitted to the inside of the tank.

Thermal performance enhancement of an oscillating heat pipe with external expansion structure for thermal energy recovery and storage

In this paper, an oscillating heat pipe (OHP) with external expansion structure and compact layout for thermal energy recovery and storage was designed and fabricated. The thermal performance of the OHP with different filling ratios (FRs) of self-rewetting fluid under continuous heating mode was tested at first. Then pulsing heating mode and alternate heating mode were explored to enhance the heat transport performance. The temperature fluctuation characteristic and the thermal resistance under different heating modes and heating periods were compared and analyzed. The result showed that the OHP can function well and sustain large heating power under appropriate range of FR. The pulsing mode and alternate mode are both helpful to increase the fluctuation frequency and amplitude of evaporator temperature. For the condition of relative low heating power and short heating period, the enhancement effect is more obvious. The thermal resistance at 100 W can be reduced by more than 10% when the heating period varies from 2 s to 10 s. Under short heating period of 0.4 s, the thermal resistance of the OHP under pulsing heating mode at 200 W can be even reduced by over 30%.