The goal of this research is to examine the applicability of the Hottel–Whillier–Bliss model, developed for flat-plate collectors, to evacuated tube solar collectors. During this study, the model is applied to an evacuated tube collector, and then the identification and validation of the model are made with the help of measurements performed on the collector. This research also includes the application, identification and validation of the energy balance model for the investigated solar collector. This model works for both flat-plate and evacuated tube collectors. The results obtained with the two different models are then compared. By comparing the modelled results with the measured values, the accuracy and applicability of the models can be determined. Based on the results, the Hottel–Whillier–Bliss model works excellently with evacuated tube solar collectors for predicting the outlet temperature of the medium from the solar collector. It is important to note that the identification gives negative heat transfer parameter values. According to the validation, the average absolute error is 0.8 °C, and the average relative error is 1%. For the energy balance model, these values are 0.87 °C and 1.1% respectively, indicating that the accuracy of the Hottel–Whillier–Bliss model is very similar, and even slightly higher. Additionally, the research provides further proof of the applicability of the energy balance model to evacuated tube collectors.

The studied solar pot is a recent invention, which is made for environmentally friendly cooking or heating (by utilizing solar energy) of foods and liquids. Its structure is similar to a double pipe heat exchanger, it has an outer mantle and an inner cooking tank. The goals of the paper are proposing a new physically-based mathematical model describing the solar pot and carrying out computer experiments with it, assembling an experimental system of the pot connected with a solar collector and performing measurements on it. Based on the results, the solar pot can successfully be used for cooking or sterilizing foods or liquids during the studied time period, in Hungary. In particular, based on measured data, the temperature level needed for heat treatment (75 °C) can be maintained in the cooking tank for several hours (~5 h, on the average) in a typical day in May.

The studied solar pot is a recent invention, which gained a utility model protection in 2021 from the Hungarian Intellectual Property Office under patent number 5489. The device is made for environmentally friendly cooking or heating (by utilizing solar energy) of foods and liquids. Its structure is similar to a double pipe heat exchanger, it has an outer mantle and an inner cooking tank. The goals of the paper are proposing a new physically-based mathematical model describing the solar pot and carrying out computer experiments with it, assembling an experimental system of the pot connected with a solar collector and performing measurements on it. Based on the results, the solar pot can successfully be used for cooking or sterilizing foods or liquids during the studied time period, in Hungary.

The subject of the research is a so-called the solar pot which is a new invention protected at the Hungarian Intellectual Property Office (utility model, patent number 5489). The pot can be used for heating or cooking (foods, drinks or other fluids). It has a similar structure to a double pipe heat exchanger with an outer jacket and an inner cooking space. Although it has been manufactured, its capabilities have not been tested neither by modelling and simulation nor with experiments and measurements, so these investigations represent a completely new research field. The goal of this work is the mathematical modelling of the pot which allows the prediction of the pot temperature. The modelling and the first simulation results based on it are presented in this paper, based on which conclusions can be drawn regarding the efficiency and applicability of the pot. Future research plan is also presented which includes the construction of an experimental system of the pot and a solar collector, and further modelling of the system and system elements. On the system, measurements will be made under different conditions, allowing the assessment of the pot’s functionality and the validation of the mathematical models.

A kutatás tárgya, a szoláris főzőedény, egy új találmány, amely a Szellemi Tulajdon Nemzeti Hivatalában, 2021-ben kapott használatiminta-oltalmat, 5489-es lajstromszám alatt. Az edény ételek, italok (vagy egyéb folyadékok) melegítésére vagy főzésére használható. Felépítését tekintve, egy cső a csőben hőcserélőhöz hasonlóan, rendelkezik egy külső köpennyel és egy belső főzőtérrel. A főzőedény fizikálisan már legyártásra került, a rajta végzett vizsgálatok folyamatosan zajlanak. A jelen munka a berendezés matematikai úton történő vizsgálatát tűzi ki célul matematikai modellek és számítógépes szimulációk segítségével. Célunk a szoláris főzőedény modellezése, amely lehetővé teszi a főzőedény hőmérsékletének előrejelzését. Bemutatásra kerül a főzőedény matematikai modellezése, valamint a modellezéshez kapcsolódó első szimulációs eredmények, amelyek alapján következtetések vonhatók le a főzőedény működésének hatékonyságára és gyakorlati alkalmazhatóságára vonatkozóan. A környezetbarát főzőedény az eredmények alapján képes főzési feladatok ellátására. Használata egy főzés alkalmával 247 grammal csökkenti a széndioxid-kibocsátást. A jövőbeni kutatási tervek között szerepel a főzőedényből és a napkollektorból álló kísérleti rendszer megépítése, a rendszer és a rendszerelemek további modellezése és a rendszeren mérések elvégzése különböző időjárási körülmények között. A tervezett kísérleti vizsgálatok majd lehetővé teszik a matematikai modellek validálását és a főzőedény működőképességének felmérését.