Adsorption refrigeration system is one of the thermal powered refrigeration that is needed to be developed due to its low performance, even though it has the advantage of utilizing low heat source in the form of either waste heat or solar energy. Its low heat and mass transfers and low specific power should be improved to increase its performance. Adsorption bed playing important role in adsorption refrigeration cycle should be improved by conducting a research on modification of activated carbon (AC) to increase their performance. Difluoromethane, famously known as R32, is chosen as adsorbate (refrigerant) since this low global warming-potential refrigerant proved high performance in vapor compression refrigeration system even though it is flammable. Local AC is chosen as adsorbent due to this material is easily found in market. The tests were conducted to obtain cooling effect, performance and the effect of final desorption temperature. An adsorption cooling system with two adsorption beds was tested by using difluoromethane with AC modified by sulfuric acid (H₂SO₄) and nitric acid (HNO₃). Both these acids can improve the performance of AC characteristics compared to that of pure AC, in which average cooling capacity increases by 6.6% for both acids, and the average coefficient of performance (COP) increases by 9.8% for HNO₃ and 5.1% for H₂SO₄. By using the final desorption temperatures of 55°C, 65°C and 75°C, the H₂SO₄ modified AC showed the cooling effect in the cooling cycle of between 17 to 36 kJ, and the obtained COP were 0.15, 0.18 and 0.20, while the specific cooling power (SCP) were between 4.4 to 6.1 W/kg AC for cycle time of 36, 40 and 50 min. The test results for HNO₃ modified AC showed the value of cooling effect ranged between 17 kJ to 37 kJ for cycle time 36, 40, and 50 min at final desorption temperature of 55°C, 65°C and 75°C, respectively. The COP ranges were from 0.14 to 0.22, while the SCP ranges were from 4.0 to 6.3 W/kg AC.

R-1243zf is a new refrigerant that could replace R-134a. Its thermodynamic properties represented in the equation of state (EOS) play an essential role in analyzing and designing thermal systems. The EOS exists without including caloric property data due to unavailable data during the development time. New EOS was developed explicitly in Helmholtz free energy and optimized to represent the experimental data accurately and maintain thermodynamic consistency. The optimization process undergoes using a genetic algorithm and weighted-least squares regression. The experimental data used in the optimization have a range of 233–430 K and 0.106–34.6 MPa and were validated from the extrapolation and consistency to confirm the reliability. The average absolute deviation from the data is 0.48% for the ideal gas isobaric specific heat, 1.7% for the isochoric specific heat, 0.33% for the speed of sound, 0.22% for the liquid density in single-phase, 0.49% for the vapor density in single-phase, 0.96% for the vapor pressure, 2.2% for the saturated liquid density, and 3.2% for the saturated vapor density. The EOS has a reasonable extrapolation behavior from the triple point up to 700 K and 100 MPa.

Solar chimneys (SCs) utilize solar-induced buoyancy to enhance natural ventilation; however, design recommendations remain challenging because of differences in modelling assumptions, thermal boundary conditions, and operating environments. This study investigates the thermal–flow characteristics and ventilation performance of a wall-mounted building-integrated SC under representative Indonesian humid-tropical conditions using OpenFOAM. The thermal predictions of the numerical model were validated against published experimental temperature data, with a maximum deviation of 3.36%. Parametric analyses of chimney cross-sectional area, height, and air gap were conducted at a constant absorbed heat flux of 500 W/m², followed by hourly quasi-steady evaluation. Chimney cross-sectional area had the greatest effect on ventilation performance, producing an air change per hour (ACH) range of 0.5–30 h⁻¹, compared with 7.7–8.6 h⁻¹ for height and 7.4–7.7 h⁻¹ for air gap. The selected configuration, with a 0.09 m² area, 3 m height, and 0.3 m air gap, achieved 4.0–10.7 h⁻¹ during hourly evaluation. The model assumes quiescent ambient conditions and dry-air Boussinesq properties; thus, wind-pressure effects and humidity-induced changes in air properties and buoyancy are not represented. These findings provide quantitative guidance for the design and assessment of building-integrated SCs in humid tropical climates within the adopted modelling assumptions.

The new system and refrigerant were introduced in heat driven adsorption refrigeration system. Adsorption refrigerator’s capability to be operated by relatively low temperature heat source has drawn considerable attention. This system can be driven by utilizing waste heat and solar energy. Positive gauge operating pressure has been pursing R-134a as the most suitable refrigerant due to its saturated temperature on high pressure and other considerations including health factor, safety, and environment. The continuous system was designed to obtain higher cooling capacity. The optimization was conducted on temperature for each process undergoing in the reactor to approximate the highest possible COP (Coefficient of Performance). The cooling capacity of the system was estimated by transient simulation on CFD software. The cooling capacity acquired by employing CFD transient simulation is 18.36 W, whereas the highest possible COP which could be attained is 0.1047 for ice-making application.