In the paper presented are experiences from operation of three different expansion devices for possible implementation in the domestic micro CHP. These were the modified scroll expander and two designs based on the variable working chamber volume pneumatic devices. Experiments showed the superiority of both "pneumatic devices" over the scroll expander, indicating the possible internal efficiencies in the range of 61 82Such efficiencies are very attractive, especially at the higher end of that range. The volume of these devices is much smaller than the scroll expander which makes it again more suitable for a domestic micro CHP. Small rotational velocities enable to conclude that connection to electricity grid will also be simpler in the case of "pneumatic devices". The "pneumatic devices" under scrutiny here could be an alternative to the typical vapour turbine in the ORC cycle, which is in the process of development at the IFFM.

The progressive processes of globalization and changes in the global, European and local economy require integrated efforts aimed at solving problems related to development at the national regional and the local level involving the environment, energy sources, climate and technological transformation issues. European Union Member States are given right to create an individual Energy mix. Coal will continue to play a major role in Poland’s energy mix during the next decades. Polish coal reserves can provide energy security for decades.

Despite crude oil and natural gas growth in fuel consumption, coal will continue to be the stabilizer of energy security for the country and play an important role in Poland’s energy mix in the years to come. However, further coal consumption requires investments in low carbon technologies which are of high efficiency and in high-efficiency cogeneration.

The validity of the full utilization of cogeneration potential should be highlighted. Operating cogeneration plants are more expensive than power plants but they are more efficient and generate less carbon emissions. In accordance with the assumptions of the Energy policy of Poland, a low-carbon economy with renewable Energy sources and nuclear Energy should be supported and developed, however the obsolete coal generators should be replaced with low-carbon high-efficient ones.

The analyzed heat accumulator is a key element in a hybrid heating system. In this paper, analytical and numerical models of the ceramic heat accumulator are presented.The accuracy of finite difference methods will be assessed by comparing the results with those obtained from the exact analytical solution.

This paper presents an analysis of the heat flow in a plate heat exchanger located at a building heat exchange station. The plate heat exchanger is the main source of heat for the building system based on microsubstations in the building apartments. The co-operation of the heat exchange station with the substations in the apartments is also described. Such microstations are intended for both domestic hot water preparation and apartment heating. The method of calculating the product of the heat transfer coefficient k and the heat exchange surface area A is presented. In order to verify the correctness of the measured values of the temperatures of hot and cold water at the heat exchange station inlet and outlet, they were compared to the values calculated using the -NTU method. Good agreement was found between the results of the calculations and the meas-urements. Recommendations were made for the temperature of return water to the heating station. The cost of operating the district heating network could be reduced by increasing the surface area of central heating radiators in apartments, so that the temperature of return water to the heating station could be lowered.