A water vapor condensation in the presence of non-condensable gases (NCG) is a very common phenomenon in process plants of various industries. The presence of even a small amount of NCG during water vapor condensation can significantly reduce the heat transfer coefficients and the efficiency of the heat exchanger. Heat exchangers with spiral tubes are widely used as condensers in process plants. Knowing the above mentioned heat transfer mechanism is necessary for optimal design of thermal appliances (apparatus) and process plants in general. A review of the open literature revealed that there are a number of works dealing with the water vapor condensation with and without the presence of NCG in straight tubes of all orientations. There are number of works dealing with condensation of refrigerants in spiral tubes used in refrigeration technology. However, when we talk about water vapor condensation in spiral tubes, it is evident from the review of the open literature that this area is still not sufficiently investigated, especially if NCG are present in mixture with water vapor. For this reason, in the present study an experimental analysis of water vapor condensation in vertical spiral tubes in the presence of NCG was conducted. Based on theoretical knowledge about the positive effects of the appearance of secondary flows in spiral tubes, and the negative effects of NCG presence on the condensation, the hypothesis of this work is that the negative effects of NCG presence during the water vapor condensation in spiral tubes are smaller comparing with other conventional geometries of heat transfer surfaces. The experimental research and analysis was performed with the following objectives: - Develop an experimental line for enabling an examination of water vapor condensation in heat exchangers with spiral tubes, with and without the presence of NCG. - Based on the experimental analysis, quantify the negative effects of NCG presence on the water vapor condensation in heat exchangers with spiral tubes. - Analyze and compare the negative effects of NCG presence on the water vapor condensation in spiral tubes and other conventional geometries of heat transfer surfaces. The experimental investigation and analysis resulted in the following: 1. Multi-purpose experimental line for enabling an investigation of thermal behavior in heat exchangers was developed and produced. The experimental line enables examinations of the thermal characteristics of heat exchangers with spiral tubes in single phase and two phase flow, with or without the presence of air as a non-condensing gas. As part of the measuring line, a system for venting non-condensable gases after the condensation process and a system that ensures that only the condensation process takes place on the complete heat transfer surface are integrated. With certain modifications, it is possible to use the same experimental line for examination of thermal behavior in other types of heat exchangers and to use other non-condensable gases. As such, it represents valuable equipment for further experimental research in the field of heat transfer. 2. Experimental methods of water vapor condensation analysis in the presence of NCG inside spiral tubes have been developed. Measurement procedures and methodology, analysis of results and comparisons with other conventional heat exchanger surfaces are described in detail. Furthermore, the methodology of developing a model of forced convection around spiral tubes is presented. 3. Based on the obtained measurement data, the negative effects of NCG presence on the water vapor condensation in spiral tubes were quantified. Negative effects are defined through the negative effect parameter (ε), which represents the ratio of the mean heat flux during condensation in the presence of NCG and the mean heat flux during condensation without the presence of NCG. It has been shown that with the increase of air mass fraction in the mixture with water vapor, the values of parameter of negative effects decrease, that is, that the negative effects of the presence of non-condensable gases are increasing. 4. Based on the obtained measurement data, in-tube heat transfer coefficients were calculated. Their dependence on the mass fraction of air as a NCG during the condensation of water vapor in spiral tubes is shown. With the increase of air mass fraction in the mixture with water vapor, the values of the heat transfer coefficients decrease. A significant decrease occurs in cases of air mass fraction in vapour up to 5 %. With a further increase in the air mass fraction, the value of the heat transfer coefficients continues to decrease, but with a lower intensity. Furthermore, the dependence of heat transfer coefficients on water vapor mass fluxes is presented. For approximately the same air mass fractions and temperature potentials, the values of the heat transfer coefficients increase with an increase of water vapor mass fluxes. 5. The quantified negative effects of the a NCG presence on the water vapor condensation in spiral tubes were compared with the corresponding negative effects in horizontal and vertical tubes, as other conventional geometries of heat transfer surfaces, with the addition of calculated combined standard measurement uncertainties. Comparable negative effects of NCG presence on the water vapor condensation in horizontal and vertical tubes are calculated according to models from literature. The comparison confirms the hypothesis that the negative effects of NCG presence during the water vapor condensation in spiral tubes are smaller compared to the same in other conventional heat transfer surfaces, with the following remarks: - The analysis carried out included a comparison of the negative effects of NCG presence during the condensation of water vapor in spiral tubes with the same negative effects in horizontal and vertical tubes, as conventional heat exchanger surfaces. - The analysis of the results explicitly confirms that the negative effect of NCG presence on the water vapor condensation in spiral tubes is smaller compared to the same in horizontal tubes. - The analysis shows that the negative effect of the NCG presence on the water vapor condensation in spiral tubes is smaller compared to the same in vertical tubes, which is shown with non-negligible certainty for air mass fractions greater than 9.3 %. For smaller air mass fractions, there are indications that the conclusions could be the same, but it is definitely advisable to conduct additional research. 6. Based on the obtained measurement data in single phase flow, a calculation model of forced convection of water around bundle of spiral tubes is developed.