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With the enactment of the Kigali amendment regarding the phase-down of substances with Global Warming Potential (GWP), refrigerants based on HFCs are falling into disuse and low-GWP refrigerants are proposed as replacements. R1233zd(E) is a promising new working fluid for High-temperature Heat Pumps (HTHPs) with low GWP which has yet to be further developed. A proper model needs to be imperatively constructed to predict the characteristics of R1233zd(E) applied in HTHPs. This paper proposes a mathematical model of two-stage compression and vapor injection heat pump system, and analyzes the compression ratio, injection mass flow rate, power consumption, discharge temperature, heating capacity and Coefficient of Performance (COP) under variable working conditions. When recovering 50 °C waste heat and supplying 60–130 °C hot water, the heating capacity increases from 2.09 to 2.22 MW and the COP decreases from 23 to 2.93. When recovering 80 °C waste heat and supplying 90–160 °C hot water, the heating capacity increases from 4.11 to 4.23 MW and the COP decreases from 24.4 to 4.59. The detailed model of heat exchangers can demonstrate the inner heat transfer process clearly, such as refrigerant temperature and gas content ratio, which would be instructive for component optimization. The above results indicate that the studied R1233zd(E)-based HTHP has excellent performance and broad application prospects, which plays a positive role in further development of HTHPs.

Renewable energy has become very prominent these days because of its sustainable and environment-friendly nature. The soil heat storage system plays an important role in the long-term storage of solar energy to ensure a consistent power supply. The experimental analysis and practical implementation of soil heat storage system are very difficult due to its large size and the simulation-based calculation is also very complex for the entire storage system. In order to reduce the system from the perspective of space and time, this paper has applied a similar function relationship for soil heat storage system and develops the traditional CFD simulation model and similar model. According to the dimensions of similar model, the corresponding experimental setup is constructed and the experimental results of long-term heat storage in the soil are compared with the calculation results of a CFD similar model. The relative error of inlet and outlet temperature difference is measured 10% and the error for soil temperature rise is below 1 °C. The proposed method has reduced the simulation and experimental workload for soil heat storage using similarity theory. Hence, the proposed method has great significance in the research domain of soil heat storage and the application of similarity theory.

Numerous novel devices have already utilized desiccant coating to implement various functions, such as atmospheric water harvesting, energy storage, and thermal/humidity management. The mathematical models employed in former literature, for instance the finite-element or finite-volume models usually suffer significant drawbacks such as extreme complexity and time-consuming. To solve this problem, this paper outlines a general strategy to develop dynamic compact thermal models of the quasi-one-dimensional sorption-based systems in the virtue of the thermal resistance-capacitance network. To be specific, the mass transfer process induced by the adsorption/desorption process is equivalent to a heat/cooling source, therefore the coupled heat and mass transfer kinetics in the corresponding device can be evaluated simultaneously. Two comprehensive experimental prototypes in our previous literature are employed to validate the effectiveness of the proposed model. The results show that our model can forecast the transient thermal behavior of the devices accurately within a few seconds. The dynamic deviation of the system output, for instance the material temperature and outlet air humidity, between simulation and experiment is within 7%. Furthermore, a parametric study is conducted based on the proposed model to analyze the influence of key parameters on system performance, showing great potential for guiding the system design and optimization.

Desiccant coated heat exchanger (DCHE) has shown great potential for dehumidification in vapor compression cooling systems and has been widely concerned in the research field of air conditioning, as well as heat and mass transfer in recent years. This paper is aimed at providing fundamental knowledge and research progresses on DCHE for dehumidification and cooling. Initially, DCHE dehumidification is chosen as the research object in this review due to its superiority of the principle by comparing with other two typical dehumidification processes, which are condensation dehumidification and rotary-wheel dehumidification. Then, intermittent dehumidification and continuous dehumidification as two operation modes of DCHE are compared. Finally, the variation characteristics of temperature and humidity during operation are discussed. The current studies of DCHE are reviewed from four aspects, including desiccant coating, cooling source, regeneration heating source and basic heat exchanger. The performance analysis of DCHE is then conducted, according to the different effects of above aspects acting on dehumidification performance, cooling performance and energy efficiency of DCHE. The ongoing researches indicate that the rational construction of DCHE is an effective way to achieve its multi-objective performance optimization. The significant progress of DCHE lays the foundation for applications on other fields. However, further research is required in the field of the selection of desiccant coatings and the structure of heat exchangers to broaden its application market.

High temperature heat pumps (HTHPs) with the output temperature above 100°C attract more and more attention in industrial heat recovery. It can effectively elevate the grade of thermal energy and recover waste heat to reduce the consumption of primary energy. In order to compare the performance of different HTHPs, six refrigerants were selected and simulated in an idealized refrigeration cycle including natural refrigerant (R718), HCs (R600, R601), HFOs (R1234ze(Z), R1336mzz(Z)) and HFC (R245fa). The simulation results showed that R718 has the best system performance and Carnot efficiency (COP/COPCarnot) among all those refrigerants. Then an R718 HTHP prototype was built to verify the feasibility of R718 high temperature output in industrial processing. The experimental comparison of R718 and R1336mzz(Z)/R600/R245fa showed that no matter compared with the novel HFO refrigerant R1336mzz(Z), the flammable HC R600 or the traditional HTHP refrigerant R245fa, R718 has its unique advantages in HTHP applications. When applied in industrial heat recovery, R718 HTHP not only can satisfy the demand for high output temperature but also has better performance.

Plant root variations and their relations with soil moisture and nutrient supply have been well documented for many species, while effects of drought, combined with extreme poor soil nutrients, on plant roots remain unclear.Herein, we addressed root vertical distributions of two typical xerophyte semishrub species, Artemisia sphaerocephala and A. intramongolica, and their relations with soil moisture, total soil nitrogen and carbon contents in arid Hunshandake desert, China. The two species experienced similar light regimes and precipitation, but differed in soil moisture and soil nutrients.Root vertical distribution patterns (e.g., coarse root diameter, root depth and root biomass) differed considerable for the two species due to high heterogeneity of soil environments. Coarse and fine root biomasses for A. intramongolica, distributed in relatively moist fixed dunes, mainly focused on surface layers (94%); but those for A. sphaerocephala dropped gradually from the surface to 140 cm depth. Relations between root traits (e.g., diameter, root biomass) and soil moisture were positive for A. intramongolica, but those for A. sphaerocephala were negative.In general, the root traits for both species positively correlated with total soil nitrogen and carbon contents. These findings suggest that both soil moisture and poor soil nutrients were the limiting resources for growth and settlement of these two species., The root traits for Artemisia sphaerocephala and A. intramongolica were positively correlated with total soil nitrogen and carbon contents. These findings indicate that both soil moisture and poor soil nutrients were the limiting resources for growth in these two species.

In order to solve the problems of atmospheric pollution and haze caused by traditional coal-fired heating, the promotion and application of clean energy heating methods is urgently needed. The air-source heat pumps are applied in the residential buildings to replace traditional coal-fired heating in Beijing and Tianjin. Limited to the cost and economic conditions, air-source heat pumps are usually installed with the traditional steel radiator. The unreasonable selection and operation of equipment can lead to low energy efficiency of partial load operation. The importance of finding an economical and efficient alternative scheme, therefore, is beyond words. The experimental research and computational fluid dynamics simulation on the performance and air distribution of air-to-air heat pump and air-to-water heat pump under the same operating conditions are done in this paper. The results demonstrate that ATAHP has bigger heating capacity than ATWHP, the decrease of the actual operation COP of ATAHP is 28.30% which is smaller than that of ATWHP by 15.45% with the ambient temperature decreasing from 7 °C to −20 °C. Thus, ATAHP is better than ATWHP at low temperature operation conditions. The temperature and velocity distribution of indoor air with ATWHP is more uniform, but the high speed air with high temperature with ATAHP blows to the head and feet directly. Consequently, the air distribution with ATAHP is more in line with the requirements of thermal comfort. To conclude, ATAHP has better performance and thermal comfort, and ATAHP is more suitable than ATWHP to be applied and popularized in northern China.

This study investigates a numerical model of an oil-free twin screw compressor with an ammonia-water mixture as refrigerant and liquid injection. The compressor was identified as the main constraint to increase the heat sink temperature of absorption-compression heat pump systems past 120 °C. Liquid injection can reduce the superheating of the vapor during compression, while an existing liquid film can provide lubrication and sealing, enabling oil-free operation. A quasi-one-dimensional numerical model was developed using the Modelica language. It considers the effects of liquid injection flows and injection positions, leakages, heat losses, and variation in ammonia mass fractions. The results revealed a strong influence of occurring internal leakages, varying ammonia mass fractions of the injected solution and changing injection flows and positions on the evolution of temperature, pressure, and compression power. The injection with a lower ammonia mass fraction is beneficial for reducing the discharge temperature, discharge pressure and compression power. The increase in injection flow led to a further reduction in the values obtained. Continuous wet compression, required for sufficient sealing and lubrication of the compressor, was achieved with injection at 360° at the beginning of the compression phase and an injection rate of about 10% of the compressor’s suction mass flow. By distributing the injection to two injection ports, wet compression can be supported and occurring under-compression and backflow can be reduced. Numerical investigation of an oil-free liquid-injected screw compressor with ammonia-water as refrigerant for high temperature heat pump applications

Summary For countries to realize their carbon neutral targets, space heating is a tough nut to crack. Passive solar heating (represented by Trombe wall) integrating thermal storage is a promising solution. However, current integrated thermal storage technologies fail to meet the demand of continuous heat supply throughout the night. Adsorption thermal batteries (ATBs) possessing ultra-high energy storage density and negligible thermal loss are enticing alternatives. Here, we present a periodic summary of advanced technologies in ATBs, put forward challenges ahead, and propose a future outlook in space heating applications. Inspired by the solar-driven chimney effect, we propose a passive ATB concept aiming to reduce the power consumption of ventilation during thermal storage and release, and moreover, provide additional humidity regulation. Based on this concept, we conceive a passive solar heating system with day and night operation, zero electricity consumption, and controllable thermal comfort.

Centrifugal heat pumps with waste heat recovery have a bright application future in industry field due to their large heating capacity and high supply water temperature. Two kinds of advanced heat pump systems are proposed and analyzed to improve the energy efficiency. The system performances are analyzed and compared for three kinds of centrifugal heat pump systems: the one-cycle two-compressor system, two-compressor parallel system, and two-cycle parallel system. According to the simulation results, the two-cycle parallel system shows great advantages in the heating capacity, power capacity, and system COP (coefficient of performance). For 30 °C evaporator inlet water temperature and 60 °C condenser outlet water temperature, the COP improvements of the two-compressor parallel system and two-cycle parallel system are 7.7% and 15.5%, respectively. When the condenser outlet water temperature is 80 °C, the system COP of the two-cycle parallel system is 9.6% and 19.0% higher than that of the one-cycle two-compressor system with 30 °C and 60 °C evaporator inlet water temperatures. The COP of the two-compressor parallel system is 5.2% and 10.2% higher than that of the one-cycle two-compressor system under the same working condition. When the temperature lift is kept at 30 °C and the condenser outlet water temperature changes from 60 °C to 90 °C, the maximum and minimum COP of two-cycle parallel system are 6.7 and 6.1, respectively, which is at least 6.8% higher than the COP of the two-compressor parallel system and 13.5% higher than that of the one-cycle two-compressor system. The experimental validation is conducted, and the results indicate that the two-cycle parallel system can satisfy the high-temperature, large-capacity, and high-efficiency requirements for industrial applications.

Various single stage ammonia-water absorption system configurations result in a confusion of determining a better one with better performance. In this paper, a unified single stage ammonia water absorption system configuration for freezing, air-conditioning, and space heating applications is proposed, and it can produce best thermal efficiencies in terms of internal heat recovery under different application conditions. The model of the unified system is established to investigate the operating parameters and the performance of the system under the representative freezing, air-conditioning, and space heating application conditions. The results verify the feasibility of the unified system, and show that the thermal efficiency is improved by 25%, 34%, and 20% respectively, compared to a conventional single stage absorption system. The calculated results also verify the key points of the system operation, which are making the feed saturated, and adjusting a proper split ratio of the strong solution to the rectifier, respectively. The 3D figures of the system thermal efficiency versus the boundary temperatures show the performance and its improvement of the unified system configuration intuitively. The cycle switching diagram is presented and provides a reference for regulating the cycle operation of the unified system.

DCHE (Desiccant coated heat exchanger) based heat pump systems can handle sensible and latent loads simultaneously and separately within one single component via flowing refrigerant and coated desiccant. Their characteristics have a crucial impact on the performance of the whole system. To ensure energy efficiency of DCHE based systems, the restriction between refrigerant and desiccant is discussed based on energy consumption analysis. Results show that energy consumption of the DCHE based heat pump is intimately related with its coefficient of performance and adsorption heat of coated desiccant. R410A and R32 are found to be promising refrigerants for DCHE systems. Maximum allowable values of adsorption heat under different ambient air conditions and sensible heat ratios are obtained. Desiccant materials with adsorption heat of 2300–3000 kJ/kg such as various silica gels, all-silica zeolites and salt supported composites are within maximum allowable values of adsorption heat for most conditions. When applying the majority of zeolite type desiccants that possess adsorption heat more than 4000 kJ/kg, great attention should be paid to the determination of supply-air temperature difference. This paper provides the underlying insights needed to guide a fast and proper selection of refrigerants and desiccants for DCHE based systems.

This paper presents a novel composite material for cold storage. Oleic acid is selected as phase change material whereas carbon coated aluminum is adopted as additive. Thermal conductivities and viscosities of samples are investigated by light flash method and viscometer. Phase change temperature and latent heat are analyzed through DSC measurements. It is indicated that thermal conductivities of composite oleic acid using nanoparticles are remarkably improved when compared with pure sample. The highest thermal conductivity of composite oleic acid with 1 wt% mass ratio of Al@C could reach 0.42 W m−1 K−1, which is 2 times higher than that of pure oleic acid. When testing temperature increases from 25 °C to 75 °C, dynamic viscosities decrease from 3.67 mPa s to 1.062 mPa s. Phase change temperature and latent heat are slightly shifted from that of pure oleic acid. This novel composite oleic acid reveals vast potentials to stabilize the performance of solar sorption cooling system.

The desiccant coated heat exchanger (DCHE), utilizing inner cooling source to ease the side effect of sorption heat, is now a hot spot in the field of humidity control. Meanwhile, when incorporated in heat pumps, the function of DCHEs is expected to be further extended. Named as solid desiccant heat pump (SDHP), such system can realize weakly-coupled temperature and humidity control both in the cooling and heating modes. Promising refrigerants are near-azeotropic mixtures, and the DCHEs in SDHP then function as desiccant-coated evaporators/condensers (DCEs/DCCs). In this paper, a comprehensive physical and mathematical description of the DCEs/DCCs is first proposed to conduct the thermodynamic analysis of the component. Furthermore, the system simulation of the SDHP validates the feasibility of the vapor compression (VC) cycle with the new type of heat exchangers (HXs), and the calculated coefficient of performance (COP) is 7.19. The precision of the component model, along with the superiority of the SDHP, is then verified by an experimental setup. The experimental study also reveals that, with the outdoor air of 35 °C, 21 g/kg (indoor 25%, 10 g/kg, 70%fresh air), the SDHP can provide cold and dry supply air of 20 °C, 8.5 g/kg and the corresponding COP reaches to 7.14.

In the face of more and more serious energy and environmental problems, energy conservation and environmental protection have attracted more attention all over the world. Combining the advantages of high temperature heat pump (HTHP) and natural refrigerant, water vapor HTHP system can effectively recover low-grade energy and is more green and environmental friendly. This paper presents a new water vapor HTHP system with 80–90 °C waste heat recovery and 120–130 °C hot water supply. The water vapor HTHP system model is established to investigate the system performance under different working conditions. Then, the experimental study of the HTHP system with water refrigerant is carried out to validate the simulation results. The simulation results present that when the evaporation temperature is under 83–87 °C and the condensation temperature among 120–128 °C, the compressor power ranges from 46.1 to 58.1 kW and system COP ranges from 3.64 to 4.87. The comparison between simulation and experimental results show good agreement with each other, which indicates that the model established in this paper has great reliability and accuracy for water vapor HTHP system.

Recent studies have reported a link between gut microbiota and nonalcoholic fatty liver disease (NAFLD), showing that germfree (GF) mice do not develop metabolic syndromes, including NAFLD. However, the specific bacterial species causing NAFLD, as well as their molecular cross talk with the host for driving liver disease, remain elusive. Here, we found that nonvirulent endotoxin-producing strains of pathogenic species overgrowing in obese human gut can act as causative agents for induction of NAFLD and related metabolic disorders. The cross talk between endotoxin from these specific producers and the host’s TLR4 receptor is the most upstream and essential molecular event for inducing all phenotypes in NAFLD and related metabolic disorders. These nonvirulent endotoxin-producing strains of gut pathogenic species overgrowing in human gut may collectively become a predictive biomarker or serve as a novel therapeutic target for NAFLD and related metabolic disorders., Gut microbiota-derived endotoxin has been linked to human nonalcoholic fatty liver disease (NAFLD), but the specific causative agents and their molecular mechanisms remain elusive. In this study, we investigated whether bacterial strains of endotoxin-producing pathogenic species overgrowing in obese human gut can work as causative agents for NAFLD. We further assessed the role of lipopolysaccharide (LPS)-Toll-like receptor 4 (TLR4) cross talk in this pathogenicity. Nonvirulent strains of Gram-negative pathobionts were isolated from obese human gut and monoassociated with C57BL/6J germfree (GF) mice fed a high-fat diet (HFD). Deletion of waaG in the bacterial endotoxin synthetic pathway and knockout of TLR4 in GF mice were used to further study the underlying mechanism for a causal relationship between these strains and the development of NAFLD. Three endotoxin-producing strains, Enterobacter cloacae B29, Escherichia coli PY102, and Klebsiella pneumoniae A7, overgrowing in the gut of morbidly obese volunteers with severe fatty liver, induced NAFLD when monoassociated with GF mice on HFD, while HFD alone did not induce the disease in GF mice. The commensal Bacteroides thetaiotaomicron (ATCC 29148), whose endotoxin activity was markedly lower than that of Enterobacteriaceae strains, did not induce NAFLD in GF mice. B29 lost its proinflammatory properties and NAFLD-inducing capacity upon deletion of the waaG gene. Moreover, E. cloacae B29 did not induce NAFLD in TLR4-deficient GF mice. These nonvirulent endotoxin-producing strains in pathobiont species overgrowing in human gut may work as causative agents, with LPS-TLR4 cross talk as the most upstream and essential molecular event for NAFLD.

From the view of environment protection, water refrigerant can completely satisfy the requirements of the energy-saving and emission-reduction. Currently, centrifugal, roots and screw compressor are three main kinds of water vapor compressors. Centrifugal water vapor compressor has the advantage of larger volume flow rate, but it has smaller single stage compression ratio, high discharge temperature, droplet sensitivity and severe and expensive blade materials. The largest volume flow rate and smallest compression ratio system is more suitable application field for centrifugal water vapor compressor. Roots water vapor compressor has the advantages of less vibration components and simple structure. However, it also has smaller compression ratio compared with screw water vapor compressor, which results in that it is usually used in the small volume flow rate, medium heating capacity and temperature rise systems. Screw water vapor compressor has the advantages of good stability, larger compression ratio and wet compression; however its volume flow rate is not very large. It is more suitable for the refrigeration system with medium and smaller volume flow rate and larger compression ratio. The main applications of water vapor compressors can be divided into mechanical vapor recompression (MVR) system, water vapor heat pump system and water vapor refrigeration system. MVR system is a high efficiency and energy saving technology and its advantages lie in the simple process, low operation cost, simple structure and small covered area. Water vapor refrigeration and heat pump systems both face the challenges of evaporation in vacuum, big compression ratio, small volumetric refrigeration capacity, large volume flow rate and high exhaust temperature. Nevertheless, the coefficients of performance (COP) of them are better than the traditional refrigeration and heat pump systems under certain conditions. Some typical applications of water vapor systems with their own special characteristics are also introduced.

A multi-criteria optimization for a biomass gasification-integrated combined cooling, heating, and power (CCHP) system based on life-cycle assessment is carried out. The criteria comprise primary energy saving ratio (PESR), total cost saving ratio (TCSR), and CO2 emission reduction ratio (CERR). The overall-performance criterion, Cl, is obtained with Technique for Order of Preference by Similarity to Ideal Solutions (TOPSIS). Results show that the Cl reaches its maximum when the nominal electric output is 1572.8 kW, the biomass feedstock type is wood pellet, and the operation strategy is following the electric load (FEL). The PESR, TCSR, CERR, and Cl are 0.101, 0.271, 0.498, and 0.867, respectively. By comparing with reference systems, it is found that in FEL mode, the system is improved because of higher energy utilization efficiency and better use of economic and environmental advantages of biomass. In following the thermal load (FTL) mode, economic performance is compromised for optimal overall performance. Sensitivity analysis is carried out to find out the effect of variation of various parameters on optimization results. It is found that the variation of a single-aspect parameter could affect the system performance on all aspects. The variation of primary energy consumption per unit electricity from the grid (pecen,g) has the greatest effect on optimization results. The corresponding variation ranges of PESR, TCSR, and CERR owing to its variation are from −0.063/0.231/0.473 to 0.284/0.295/0.624 and from −0.029/0.101/0.314 to 0.194/0.123/0.379 in FEL and FTL modes.

Indoor air quality including temperature, humidity and cleanliness has attracted more and more attention recently. Rotary desiccant wheel system provides a good solution to improve indoor air quality due to it can realize both TVOC and moisture control. In order to analyze practical performance of desiccant wheel, in this paper an experimental setup is built and TVOC removal as well as moisture removal capacity of silica gel desiccant wheel is discussed. Performance of the wheel is evaluated by the removal efficiency of TVOC (Ec) and moisture (Ed). Experiments are firstly conducted under mild environmental condition with moderate temperature and humidity ratio to analyze effects of main parameters on TVOC removal efficiency, and it is found that Ec increases with the increasing of regeneration temperature, also under experimental condition the required regeneration air temperature range for TVOC removal fits with the regeneration temperature for dehumidification. Then under Shanghai summer condition the combined removal capacity of TVOC and moisture under the same regeneration air temperature is discussed. Results show that regeneration temperature higher than 100°C is recommended under experimental conditions to meet both needs from TVOC and humidity load. Also under this condition, dehumidification capacity of the system is greatly affected by ambient humidity ratio but keep fixed with changing of TVOCA concentration, and TVOC removal capacity is influenced both by ambient humidity condition and contaminant concentration.

Solid sorption and kinetic models are important for both experimental and theoretical analysis of chemisorption refrigeration and energy storage. This review attempts to present clear overview of the reaction kinetics of chemisorption working pairs (mainly the metal halide-ammonia working pairs). The typical equilibrium principles and phenomena in metal halide-ammonia working pairs are introduced. The advantages and shortcomings of several classical non-equilibrium models have been analyzed comprehensively and new chemisorption phenomena of metal halide-ammonia working pairs that have been recently discovered are discussed. Finally, new directions for the development of kinetic models for metal halide-ammonia working pairs are proposed.

Nitrogen (N) is a major limiting element for productivity in temperate grasslands, particularly during early spring when soil N availability is low and the vegetative demand for it is high. Therefore, knowing whether and how plant species adopt different N acquisition strategies during the winter-spring transitional period is essential for understanding ecosystem functioning in temperate grasslands. In this study, parallel experiments with 15N tracer were conducted to examine plant N acquisition strategies during winter-spring transition in a meadow and a typical steppe in northern China. We found that soil microbes immobilized ∼20% of the 15N tracer during the spring thawing period at both sites, and then released half of it back to the soil before late spring, confirming that soil microbes competed effectively with the plant roots for mineral N in early spring. Perennial bunch grasses adopted an active N acquisition strategy at the beginning of the spring thawing period. In contrast, perennial forbs and rhizome grasses began to take up N in the middle of the spring thawing period, and they acquired more N than the bunch grasses. However, sagebrushes and legumes accounted for little 15N recovery, indicating their dependence on internal N accumulation or N fixation. At the ecosystem level, no significant difference in the magnitude of plant 15N uptake was observed between the meadow steppe and typical steppe, although the plant biomass N in the meadow steppe was twice that of the typical steppe during the thawing period. This was attributed to the higher soil inorganic N and faster net N mineralization rate in the meadow steppe than in the typical steppe. Our results suggest that temporal niche differentiation in N acquisition during early spring may facilitate species coexistence in temperate grasslands despite strong plant-microbe or plant-plant competition for N. The divergent N acquisition strategies at the species level and convergent N acquisition strategies at the ecosystem level should be considered for model development to better simulate vegetation growth particularly under spring N stress.

Desiccant-coated heat exchanger (DCHE) is a novel component for handling both sensible and latent heat assisted by desiccant materials. In this paper, three types of DCHEs with the same transfer surface area, DCHE A (fin pitch 2 mm, fin depth 44 mm), DCHE B (fin pitch 3 mm, fin depth 66 mm) and DCHE C (fin pitch 4 mm, fin depth 88 mm), are fabricated to make out the relationships between structure sizes and performance characteristics. The transient heat and moisture transfer performance, as well as the pressure drop passing through DCHEs, are tested and compared in depth. By using Taguchi method, the ranks of influence factors in heat and mass transfer performances are obtained. With the same transfer surface area but different surface compactness, three DCHEs show different heat and mass transfer capacities and different pressure drops. DCHE A with the highest surface compactness shows the highest heat and mass transfer capacity, while the highest pressure drop is shown as deficiency. DCHE C with the smallest surface compactness shows the highest heat recovery efficiency and the lowest pressure drop. Heat transfer coefficient of DCHE A is 14.9% greater than DCHE B, 19.6% greater than DCHE C in dehumidification process. The moisture adsorbed value of DCHE A is 9.6% greater than DCHE B, 18.2% greater than DCHE C. Pressure drop of DCHE A is 50% larger than DCHE B, and 90% larger than DCHE C. The correlations of Nusselt number and Euler number of three DCHEs are summarized by fitting the experimental data.

Hybrid solid desiccant and vapor compression system is developed to realize independent control of temperature and humidity. However the large volume has always hindered further development and heat pump system based on desiccant coated heat exchanger (DCHE) is proposed to solve the problem. It’s DCHE instead of conventional sensible heat exchanger is adopted as evaporator/condenser in this system, which also serves as a bridge to link conventional solid desiccant system and vapor compression system together. Simulation model is established in this paper to analyze system performance operating as separate air conditioner. It is found that under new operation condition with higher evaporation temperature and taking COP, pressure and flammability into account, R134a is recommended as refrigerant. Switch time is identified as crucial parameter to avoid condensation. In full fresh air mode, 20–300 s and 30–180 s are the recommended switch time under ARI summer and humid conditions respectively. Also, switch time around 100 s can obtain the highest cooling capacity. For hot and humid summer time in Shanghai, the system can’t meet the indoor requirement with full fresh air mode. However, decreasing the handled load is proved to be effective method. Also the system can obtain the overall COP as high as 5.8 under simulation conditions.

This letter is intended to reply to the Letter to the Editor by A. Bejan and closure the discussion on the authors' published article that proposed the temperature–heat ( T – Q ) diagram methodology for adsorption refrigeration. Dr. Bejan asserted his ownership of the “ origin ” of this method and reaffirmed the “ falsehood ” of entransy in his letter. In this reply, the authors give answers and rebuttals to Dr. Bejan's comments and make some points about the academic debate on entransy.

A novel resorption cycle with internal heat recovery process is proposed, which is expected to further explore potentials of power and refrigeration cogeneration. Two sets of basic resorption refrigeration cycles are adopted, which are integrated with turbine/expander to realize quasi-continuous output in both half cycles. An improved cogeneration efficiency could be obtained with safety feature. Different ammonia composite sorbents with better heat and mass transfer performance are selected to investigate the overall performance when heat source temperature is in the range from 200 °C to 360 °C. It is indicated that energy efficiency for power generation is able to reach up to 0.263 at 360 °C heat source temperature while refrigeration coefficient of performance could achieve up to 1.31 at 200 °C heat source temperature. The optimal total exergy efficiency of novel resorption cogeneration cycle is as high as 0.74 by using working pair of FeCl2-CaCl2-BaCl2 at 240 °C heat source temperature. Compared with other sorption cycles for power and refrigeration cogeneration at similar heat source temperatures, the proposed resorption cycle exhibits the highest exergy efficiency, which is about 30% higher than that of water-ammonia sorption cogeneration cycle, and twice higher than that of basic resorption cogeneration cycle.