Liquid Heat Capacity Research Articles

Thermodynamic and Physical Property Estimation of Compounds Derived from the Fast Pyrolysis of Lignocellulosic Materials

The development of biomass pyrolysis oil refineries is a very promising path for the production of biofuels and bioproducts from lignocellulosic materials. Given that bio-oil is a complex mixture of organic compounds, the production of valuable bioproducts may imply the use of different separation processes, such as distillation, selective condensation, crystallization based on melting points, liquid–liquid extraction or adsorption, and/or upgrading treatments, such as catalytic cracking or hydrodeoxygenation. In this context, the main objectives of this work are (1) to propose a simple but representative composition of the bio-oil, which can be used as a bio-oil surrogate, and (2) to determine selected thermodynamic, physical, and molecular properties of the organic compounds included in the bio-oil surrogate using different estimation methods and calculation procedures. These properties are critical temperature, critical pressure, critical volume, normal boiling point, enthalpy of vaporization, vapor pressure curves, normal melting point, enthalpy of fusion, heat capacities of gas, liquid, and solid, gas and liquid standard enthalpy of formation, gas standard Gibbs free energy of formation, Hansen solubility parameters, molecular volume, and molecular diameter. This group of properties has been selected for their possible application in the simulation or design of thermochemical, separation, and upgrading processes. Additionally, the suitability of the estimated thermodynamic properties and the proposed surrogate composition has been assessed by comparing experimental and literature data with the apparent enthalpy of formation of the bio-oil predicted from the weight-averaged contributions of the compounds as well as the heat required for the pyrolysis process at 500 °C.

The isobaric heat capacity of 2,3,3,3-tetrafluoroprop-1-ene (R1234yf) at temperatures from (230 to 285) K and pressures up to 8 MPa using a new flow calorimeter

In this paper, a new flow calorimeter was developed to measure the isobaric specific heat capacity (cp) of liquids. The uncertainties of temperature, pressure, and cp were estimated to be less than 11 mK, 0.02 MPa and 1.26%, respectively. The pure 1,1,1,2-tetrafluoroethane (R134a) was measured at temperatures from (230 to 285) K to quantitatively calculated the heat leakage at different temperatures. In order to verify the reliability of apparatus, the cp for R134a and difluoromethane (R32) were obtained at temperatures from (230 to 285) K and pressures up to 8 MPa. Measurements of R134a and R32 show good agreement with the reported data and the high-precision Helmholtz energy equations of state (EoSs). Finally, a total of 33 cp data for 2,3,3,3-Tetrafluoroprop-1-ene (R1234yf) were obtained at temperatures from (230 to 285) K and pressures up to 8 MPa. The presented cp data show good agreement with the published data and two Helmholtz energy EoSs developed by Akasaka et al. and Richter et al. with the average absolute relative deviations (AARDs) of 0.92% and 1.80%, respectively. The Helmholtz energy EoS developed by Akasaka et al. gives a better prediction performance for the cp of R1234yf at low temperature than the other EoS.

Heat capacities of selected active pharmaceutical ingredients

Condensed-phase heat capacities of selected pharmaceutical active pharmaceutical ingredients (APIs), namely (RS)-ibuprofen (CAS RN: 15687-27-1), (S)-ibuprofen (CAS RN: 51146-56-6), (S)-naproxen (CAS RN: 22204-53-1), indomethacin (CAS RN: 53-86-1), and carbamazepine (CAS RN: 298-46-4), were determined using Tian-Calvet calorimetry and power-compensated differential scanning calorimetry in the temperature range 216 to 471 K. In most cases, previously published heat capacities of the studied APIs are in significant disagreement both with each other and our measurements. By analyzing the literature values, many previously published data sets were shown to be erroneous. The heat capacities of supercooled liquid, an important parameter in the modeling of API solubility, were also measured in a wide temperature range when feasible. The phase behavior study of carbamazepine suggests that its thermal stability is lower than previously thought, which is in accordance with the most recent studies on carbamazepine decomposition. This work significantly extends the availability of reliable API heat capacity data for clearly defined polymorphic forms and liquid phase.

Heat capacity, entropy, configurational entropy, and viscosity of magnesium silicate glasses and liquids

In this work, five Mg-silicate glasses with compositions between MgSiO_3 and Mg_2SiO_4 were synthesized by aerodynamic levitation combined with laser melting. Low-temperature heat capacity (C_p) was measured (by relaxation calorimetry in the range 2–310 K) for all of them, with the resulting vibrational entropies at T = 298.15 K: sample MG50 with composition Mg_{0.996}SiO_{2.996} and entropy 72.88 J mol^{-1} K^{-1}; MG54 Mg_{1.174}SiO_{3.174} 78.54; MG58 Mg_{1.364}SiO_{3.364} 85.05; MG62 Mg_{1.611}SiO_{3.611} 91.40; and MG67 Mg_{1.907}SiO_{3.907} 102.75. Heat capacity of the glasses is higher than that of the corresponding crystal mixtures below 200 K but plunges below the C_{p,mathrm{crystal}} at higher temperatures. High-temperature C_p was measured (by differential scanning calorimetry in the range 300–970 K) for MG50 and MG67 up to approx 1000 K. Using our C_p data, selected data for entropies of fusion, C_p of crystals, and fictive temperatures, the configurational entropy (S_mathrm{conf}) at glass transition temperature (T_mathrm{g}) were calculated. For the near-forsterite glass MG67, the S_mathrm{conf} is 1.9 J mol^{-1} K^{-1} at T_mathrm{g} = 1040 K. As this small value is a difference of several large numbers, its uncertainty is relatively high; we consider a conservative estimate of 15 J mol^{-1} K^{-1}. Using the expression log eta = A + B/[T S_mathrm{conf}(T)], the available experimental viscosities (eta ) and the temperature-dependent configurational entropy from our work, we refined the parameters A = -2.34 and B = 76,500 for this equation, with S_mathrm{conf} (T) = 1.90+(83.7 ln (T/1040)). The configurational entropy for the enstatitic MG50 glass is 16.8 J mol^{-1} K^{-1} at T_mathrm{g} = 1063 K. The presented data can be combined with enthalpies of formation and thermophysical properties of Mg-silicate glasses for models that could elucidate geological and geophysical observations in the crust and mantle of the Earth.

Comparison of isochoric and isobaric heat capacities of liquid organic non-electrolytes and their vaporization enthalpies

The present paper is devoted to the study of the relationship between the difference of isochoric heat capacities of liquid and ideal gas phase organic non-electrolytes and their vaporization enthalpy at 298.15 K. This investigation is intended to more deeply analyze the origin of the recent finding that the difference of isobaric heat capacities of organic compounds in liquid and ideal gas phase is in a linear correlation with the vaporization enthalpy. We showed that the difference of isobaric and isochoric heat capacities of liquid aromatic compounds is constant within 3 J·K−1·mol−1 and does not depend on the vaporization enthalpy. A direct proportionality between isochoric heat capacity change and the vaporization enthalpy was established for 84 compounds, which included not only aromatic liquids but other rigid and relatively inflexible molecules (root-mean-square deviation equaled 2.5 J·K−1·mol−1). The slope agreed with that of isobaric heat capacity change – vaporization enthalpy correlation. Statistical significance of the established relationship far exceeded correlations with other molecular size-related parameters, namely the heat capacities, molar volume, and molecular weight.

Expansion Velocity Model of Steam-Assisted Gravity Drainage considering Thermal Convection

Steam-assisted gravity drainage (SAGD) is an important method used in the development of heavy oil. A heat transfer model in the SAGD production process is established based on the heat transfer effect caused by the temperature difference at the front edge of the steam chamber and the heat convection effect caused by the pressure difference. The observation well temperature method is used in this model to calculate the horizontal expansion speed of the steam chamber. In this manner, an expansion speed model considering heat convection and heat conduction is established for a steam chamber with a steam-assisted gravity drainage system. By comparing this with the production data extracted from the Fengcheng Oilfield target block, it is verified that the model can be effectively applied for actual field development. Simultaneously, by using the derived model, the temperature distribution at the edge of the steam chamber and production forecast can be predicted. Sensitivity analysis of the expansion rate of the steam chamber demonstrates that the larger the thermal conductivity, the faster is the steam chamber horizontal expansion speed, and the two are positively correlated; the larger the reservoir heat capacity, the slower is the steam chamber horizontal expansion speed. A larger heat capacity of the convective liquid indicates that there are more water components in the convective liquid, the viscosity of the convective liquid is low, and the expansion speed of the steam chamber increases accordingly. This research closely integrates theory with actual field production and provides theoretical support for the development of heavy oil reservoirs.

Phonon gas model for thermal conductivity of dense, strongly interacting liquids

Developing predictive thermal property models for liquids based on microscopic principles has been elusive. The difficulty is that liquids have gas-like and solid-like attributes that are at odds when considering the frameworks of microscopic models: Models for gases are simple due to randomness and low density, whereas models for crystalline solids rely on symmetry and long-range order for easier calculation. The short-range order in liquids does, however, provide structure to neighboring molecules similar to amorphous solids, and there have been recent advances indicating that collective vibrational modes store heat in liquids. Models combining Debye approximations from solid-state physics and Frenkel’s theory of liquids can accurately predict the heat capacity of liquids. Phonon-like dispersions in liquids have also been widely observed in neutron scattering experiments. These developments motivate us to propose a model where high-frequency vibrational modes, which travel at the speed of sound and have a mean free path on the order of the average intermolecular distance, conduct heat in liquids. We use this liquid phonon gas model to calculate the thermal conductivity of liquids with varying intermolecular interaction energies from strongest to weakest—Coulomb, hydrogen-bonding, Keesom, and London dispersion energy. Generally, the model is more accurate as the intermolecular interaction energy and density of liquids increase. The calculated thermal conductivity of Coulombic-bound molten sodium nitrate and hydrogen-bonded water is within 1.46% and 2.98% of the experimentally measured values, respectively, across their entire temperature ranges. Further modal analysis of the velocity and the mean free path of collective vibrations could establish the liquid phonon gas model as an accurate model for weakly interacting liquids as well.

Machine learning specific heat capacities of nanofluids containing CuO and Al2O3

AbstractEmpirical work and modeling approaches have shown that fundamental thermophysical parameters of constituents, nanoparticles, and base liquids have complex but synergistic effects on the specific heat capacity of nanofluids. In this work, we develop the Gaussian process regression model to investigate the statistical relationship among temperature, specific heat capacities of nanoparticles and base liquids, nanoparticle volume concentrations, and specific heat capacities of nanofluids. The model is developed with a dataset containing nanofluids with CuO and Al2O3 nanoparticles, and water and ethylene glycol (EG) as base liquids. The model also applies well to nanofluids containing mixtures of water and EG, and Al2O3 nanoparticles with different particle size distributions. The model is highly accurate and stable that contributes to fast and low‐cost estimations of specific heat capacities of nanofluids over a wide range of compositions and temperature.

Investigation uncovered the impact of anions on CO2 absorption by low viscous ether functionalized pyridinium ionic liquids

Ionic liquids, which are designable and nonvolatile, have become a hot topic in the field of CO2 separation from industrial gases. In order to utilize the nonvolatile and low heat capacity of ionic liquids, it is necessary to solve the problem of high viscosity of pure ionic liquids. In the present study, ether functionalized pyridinium ion [E1Py]+ with good biodegradability and low viscosity was selected as cation. Ions containing cyano groups were used as anions, such as thiocyanate ion [SCN]-, dicyanamide ion [N(CN)2]-, tricyanomethanide ion [C(CN)3]-. Three ionic liquids with low viscosity were synthesized and characterized by 1HNMR, 13CNMR and FTIR. The physiochemical properties of ionic liquids such thermal decomposition temperature, density and viscosity were tested. The CO2 absorption capacity was systematically studied by using intelligent gravimetric analyzer at the pressure range between 0 and 15 bars and the temperature range from 303.15 to 333.15 K. The results showed that the order of CO2 absorption capacity of these three ionic liquids is [E1Py][C(CN)3] > [E1Py] [N(CN)2] > [E1Py][SCN], which showed that the solubility increased by increasing more cyano groups in ionic liquids. Thermodynamic properties such as enthalpy, entropy, and Gibbs free energy were also calculated for CO2 absorption.

Measurements of isochoric specific heat capacity for 3,3,3-trifluoroprop-1-ene (R1243zf) at temperatures from (250 to 300) K and pressures up to 10 MPa

In this paper, a total of 86 isochoric specific heat capacity (cv) data of 3,3,3-trifluoroprop-1-ene (R1243zf) at temperatures from (250 to 300) K and pressures up to 10 MPa were measured using an adiabatic batch calorimeter. The standard uncertainties of temperature, pressure and isochoric specific heat capacity were estimated to be 12 mK, 5 kPa and 0.95%, respectively. A comparison was conducted between the experimental cv data and values calculated by three equations including the Helmholtz energy EOS (Akasaka and Lemmon, 2019) in REFPROP 10.0, the generalized equation (Zhong et al., 2019) and the corresponding states equation (Sheng et al., 2020) with the average absolute relative deviations (AARDs) of 2.43%, 0.91% and 0.84%, respectively. Among three equations, the corresponding states equation developed by Sheng et al. gives the best predictive performance for the liquid heat capacity of R1243zf.

Relationship between the vaporization enthalpies of aromatic compounds and the difference between liquid and ideal gas heat capacities

Understanding connection between physicochemical parameters, molecular structure and heat capacity of liquids remains limited, especially for complex organic molecules. One of possible ways to resolve this problem is analysis of difference between the liquid and ideal gas heat capacities. This difference also defines the temperature dependence of vaporization enthalpy.This work is based on the assumption that the difference between the liquid and gas phase heat capacity is primarily related to intermolecular interactions in the liquid. As the measure of intermolecular interactions, the vaporization enthalpy at 298.15 K was considered. The relationship between the difference of liquid and gas phase heat capacities and the vaporization enthalpy was analyzed for a wide range of aromatic and heteroaromatic compounds. An excellent correlation was observed (residual standard deviation 3.7 J·K−1·mol−1, N = 99). This correlation appeared to be useful for estimation of the vaporization enthalpies of aromatic compounds at elevated temperatures solely from the value at 298.15 K. The calculated and literature vaporization enthalpies measured between 360 and 650 K of 80 compounds from 134 sources were compared. An average absolute deviation of 1.5 kJ·mol−1 was observed, being competitive with the experimental errors of vaporization enthalpy determination.

Jumping transition in the liquid's heat capacity revealed by the scanning transitiometry

AbstractThis manuscript reports the direct observations of the clear jump transition of the specific orthobaric heat capacity to the specific isochoric heat capacities during the continuous heating of liquid samples in a closed vessel as well as the respective theory explaining such effects. The measurements have been performed with n‐heptane and toluene and the results have been thoroughly analyzed with the derived equations and compared with the values from the known literature data. The detection and accurate tracking of a jump in the heat capacity far from the standard points of phase transitions are not only of fundamental thermodynamic interest but also demonstrates future research targets and now attainable data which can be achieved by modern calorimetric technology. It has been proven that by using high‐pressure scanning calorimeter (transitiometry technology) it is possible to directly measure the specific orthobaric heat capacities and specific isochoric heat capacities accurately.

A corresponding state equation for compressed liquid isochoric heat capacity of pure and mixture refrigerants

• A simple corresponding state equation for compressed liquid isochoric heat capacity of pure and mixture refrigerants was developed. • The present equation contains two constant coefficients and only depends on reduced temperature. • The equation is in good agreement with compressed liquid c v experimental data of pure and mixture refrigerants. • The equation can be used to predict c v of pure and mixture refrigerants in compressed liquid states. This work proposed a simple corresponding state equation depending on reduced temperature to predict compressed liquid isochoric heat capacity ( c v ) for HCs, HCFCs, HFCs and HFOs pure and mixtures at 0.3 < T r < 1 and 0.5 < p r < 10. The generalized constant coefficients A and B were determined by regression of 1738 experimental c v data for 16 refrigerants including HCs, HFCs, HCFCs and HFOs in compressed liquid states ( ρ > 2 ρ c ). With known critical parameters, acentric factor and ideal gas isochoric heat capacity, the developed equation can represent the compressed liquid c v well with the average absolute relative deviation (AARD) of 1.82%. Compared with the generalized equation of Zhong et al. (2019a) and the special multiproperty equations in REFPROP 10.0 software, the proposed equation is slightly poor in accuracy, but simpler in form and requires fewer parameters. In addition, liquid c v data of 13 pure and 9 mixtures were used to verify the prediction performance of the developed equation and the applicability to the mixtures. The equation in this work is in good agreement with the experiment c v data of 9 pure and 9 mixtures including HCs, HFCs, HCFCs and HFOs, but the large deviation for 4 substances (N 2 , CO 2 , H 2 O and CH 3 OH).

Numerical simulation of flashing using a pressure-based compressible multiphase approach and a thermodynamic cavitation model

A recently published pressure-based compressible multiphase flow model Labois and Narayanan (2017) is validated for applications relevant to safety of pressurized systems, such as flashing of high-pressure water through valves and nozzles. The pressure-based compressible multiphase flow solver is based on non-conservative discretization of the mixture continuity equation and has the advantage of being applicable to interface tracking and n-phase mixture formulations. For simulation of flashing, two well-known cavitation models Singhal et al.(2002), Yuan et al.(2001) have been implemented along with thermodynamic effects such as latent heat of phase change, variable saturation pressure, and heat capacities. The limitations of the well-established cavitation models in terms of their applicability to compressible flows have been clarified. The model was applied to the Super Moby Dick experiment Rousseau (1987). Good flow rates, and pressure and void fraction variations were obtained for three chosen conditions by tuning the cavitation model under incompressible conditions. It was found that the void fraction stops increasing beyond the throat due to thermodynamic effects where the latent heat and heat capacity are functions of pressure and temperature. The reduction of latent heat and rapid changes in liquid and vapour heat capacities close to the saturation line at high pressures was shown to be important. The accuracy, robustness, and efficiency of the pressure-based method has been proven for flashing under strong depressurization conditions. The cavitation model predictions are strongly sensitive to model parameters such as the nucleate density making the models not general enough to be applied to different problems without calibration. It was shown that there is significant room for development of improved cavitation models especially focussing on the constant number density constraint due to the strong sensitivity of the current models to this input parameter. The assumption of incompressibility and homogeneity of the phasic velocities is also identified as serious limitations requiring further study.

Prediction and verification of heat capacities for pure ionic liquids

The heat capacity of ionic liquids is an important physical property, and experimental measuring is usually used as a common method to obtain them. Owing to the huge number of ionic liquids that can be potentially synthesized, it is desirable to acquire theoretical predictions. In this work, the Conductor-like Screening Model for Real Solvents (COSMO-RS) was used to predict the heat capacity of pure ionic liquids, and an intensive literature survey was conducted for providing a database to verify the prediction of COSMO-RS. The survey shows that the heat capacity is available for 117 ionic liquids at temperatures ranging 77.66–520 K since 2004, and the 4025 data points in total with the values from 76.37 to 1484 J·mol−1·K−1 have been reported. The prediction of heat capacity with COSMO-RS can only be conducted at two temperatures (298 and 323 K). The comparison with the experimental data proves the prediction reliability of COSMO-RS, and the average relative deviation (ARD) is 8.54%. Based on the predictions at two temperatures, a linear equation was obtained for each ionic liquid, and the heat capacities at other temperatures were then estimated via interpolation and extrapolation. The acquired heat capacities at other temperatures were then compared with the experimental data, and the ARD is only 9.50%. This evidences that the heat capacity of a pure ionic liquid follows a linear equation within the temperature range of study, and COSMO-RS can be used to predict the heat capacity of ionic liquids reliably.

Vapor Pressures and Thermophysical Properties of 1-Heptanol, 1-Octanol, 1-Nonanol, and 1-Decanol: Data Reconciliation and PC-SAFT Modeling

Vapor pressures for liquid 1-heptanol (CAS RN: 111-70-6), 1-octanol (CAS RN: 111-87-5), 1-nonanol (CAS RN: 143-08-8), and 1-decanol (CAS RN: 112-30-1) were measured by a static method near ambient temperatures over an operating pressure range from 0.5 to 1270 Pa, thus complementing literature vapor pressure data obtained by ebulliometry at higher temperatures. Liquid heat capacities of 1-octanol, 1-nonanol, and 1-decanol were determined by Tian–Calvet calorimetry. Ideal-gas thermodynamic properties of 1-alkanols up to 1-heptanol were obtained by a combination of quantum chemistry and statistical mechanics and validated against available experimental data. Ideal-gas heat capacities and entropies for longer homologues were obtained by deriving a methylene increment due to having a too complex conformational shape for analogical treatment. The thermodynamic consistency of available data was validated by simultaneous correlation of selected vapor pressures, literature enthalpies of vaporization, and heat capacity differences between the ideal gaseous and the liquid phase. The results are represented by the Cox equation and compared with available literature data. Moreover, the results were used to examine the perturbed-chain statistical associating fluid theory (PC-SAFT) equation of state for its performance in describing vapor pressures, enthalpies of vaporization, residual liquid heat capacities, and liquid densities of neat 1-alkanols from 1-hexanol to 1-decanol. A new PC-SAFT parameter set for each of them was also regressed that improves the PC-SAFT performance for the studied properties in comparison to existing parameters published in the literature.

Friction-reducing properties of N-containing ionic liquid additives by using quantitative structure tribo-ability relationship model

The purpose of this paper is to study the friction-reducing properties of 23 N-containing heterocyclic ionic liquid additives in polyethylene glycol 400 (PEG-400) or dimethyl sulfoxide (DMSO). Based on the theory of quantitative structure tribo-ability relationship (QSTR), the quantum chemical parameters of 23 N-containing heterocyclic ionic liquid molecules were calculated by density functional theory, and the friction-reducing properties of the ionic liquid additives in PEG-400 or DMSO were studied by multiple linear regression. The results show that QSTR models with excellent stability and strong prediction abilities were obtained for both polar liquids studied. Heat capacity of the ionic liquid is the main quantum chemical parameter affecting its friction-reducing performance. The friction-reducing performance of the selected ionic liquid additive in DMSO is better than that in PEG-400. A friction-reducing mechanism is also discussed.

Investigation on the thermal performances of [Na(TX-7)]SCN/NH3 absorption systems based on physical properties measurement of the working fluid

The application of ionic liquid in the ammonia absorption system is current research hotspot. The low solubilities of ammonia in common ionic liquids lead to poor thermal performances of absorption systems, which is the main obstacle faced by ionic liquid absorption systems. Hence, we proposed a new idea of using ionic liquids containing metal cations to enhance the thermal performances of the absorption systems. The specific ionic liquid being studied is [Na(TX-7)]SCN. The vapor–liquid equilibrium and heat capacities of [Na(TX-7)]SCN/NH3 were studied by experimental methods. Based on above physical properties, the thermal performances of absorption refrigeration and absorption heat transformer using [Na(TX-7)]SCN/NH3 were simulated and compared with those of other systems. The thermal performances of [Na(TX-7)]SCN/NH3 absorption refrigeration are better than NH3/H2O system and other ionic liquid systems, but is a bit lower than NaSCN/NH3 system. The thermal performances of [Na(TX-7)]SCN/NH3 absorption heat transformer are better than those of the [mmim]DMP/H2O and [mmim]DMP/CH3OH systems, similar to those of the NaSCN/NH3 system, and slightly lower than those of the LiBr/H2O system. Overall, the proposed working fluid obviously improves the thermal performances of ionic liquid system and solves the crystallization problem of NaSCN/NH3 and LiBr/H2O systems.

Modeling of liquid internal energy and heat capacity over a wide pressure–temperature range from first principles

Recently, there have been significant theoretical advances in our understanding of liquids and dense supercritical fluids based on their ability to support high frequency transverse (shear) waves. Here, we have constructed a new computer model using these recent theoretical findings (the phonon theory of liquid thermodynamics) to model liquid internal energy across a wide pressure–temperature range. We have applied it to a number of real liquids in both the subcritical regime and the supercritical regime, in which the liquid state is demarcated by the Frenkel line. Our fitting to experimental data in a wide pressure–temperature range has allowed us to test the new theoretical model with hitherto unprecedented rigor. We have quantified the degree to which the prediction of internal energy and heat capacity is constrained by the different input parameters: the liquid relaxation time (initially obtained from the viscosity), the Debye wavenumber, and the infinite-frequency shear modulus. The model is successfully applied to output the internal energy and heat capacity data for several different fluids (Ar, Ne, N2, and Kr) over a range of densities and temperatures. We find that the predicted heat capacities are extremely sensitive to the values used for the liquid relaxation time. If these are calculated directly from the viscosity data, then, in some cases, changes within the margins of the experimental error in the viscosity data can cause the heat capacity to exhibit a completely different trend as a function of temperature. Our code is computationally inexpensive, and it is available for other researchers to use.

Liquid Thermo-Responsive Smart Window Derived from Hydrogel

Summary Buildings account for 40% of global energy consumption, while windows are the least energy-efficient part of buildings. Conventional smart windows only regulate solar transmission. For the first time, we developed high thermal energy storage thermo-responsive smart window (HTEST smart window) by trapping the hydrogel-derived liquid within glasses. The excellent thermo-responsive optical property (90% of luminous transmittance and 68.1% solar modulation) together with outstanding specific heat capacity of liquid gives the HTEST smart window excellent energy conservation performance. Simulations suggested that HTEST window can cut off 44.6% heating, ventilation, and air-conditioning (HVAC) energy consumption compared with the normal glass in Singapore. In outdoor demonstrations, the HTEST smart window showed promising energy-saving performance in summer daytime. Compared with conventional energy-saving glasses, which need expensive equipment, the thermo-responsive liquid-trapped structure offers a disruptive strategy of easy fabrication, good uniformity, and scalability, together with soundproof functionality that opens an avenue for energy-saving buildings and greenhouses.